Murder and manslaughter charges have been filed against Derek Chauvin, the officer who prosecutors say held his knee on Floyd's neck for nearly nine minutes.
Chauvin and the other three officers at the scene have been fired. The Department of Justice is investigating.
Monday's biggest developments:
This is how the news unfolded on Monday. All times Eastern.
11:32 p.m.: Store windows smashed in Manhattan shopping spots
In New York City, vandals smashed store windows and attempted to loot several stores at Midtown Manhattan locations frequented by tourists.
Police confronted attempted looters as they smashed into a boutique tea shop in the middle of Rockefeller Center.
NYPD officers also responded to reports of shattered windows at The Nintendo Store, Michael Kors, Kate Spade, and Barnes and Noble. Mannequins could be seen on the broken glass-covered sidewalks. Police made one arrest after tackling a man to the ground.
Looting also took place further downtown, where looters were caught on camera breaking into a Nordstrom Rack in Union Square.
10:42 p.m.: Police injured in Buffalo, clashes continue in Louisville
Authorities in Buffalo say two officers were stuck when a vehicle plowed into a group of law enforcement officers during a protest. Injuries to one of the officers appear serious in nature, officials say.
State Police members were helping Buffalo Police disperse protesters on Bailey Avenue when the vehicle drove into the officers, according to authorities.
Police in Louisville, Kentucky, flooded the street with tear gas and used flash bangs to clear protesters from the area around Seventh and Jefferson streets. The move came a night after police used similar tactics to flush protesters from Jefferson Square Park, in a move that was questioned by some city officials, according to the Louisville Courier Journal.
Two people were also struck by gunfire in a separate incident, Buffalo Police say.
Protesters in Dallas marched onto the Margaret Hunt Hill Bridge and blocked traffic before police made several arrests.
10:11 p.m. More arrests as cities begin 10 p.m. curfew
Police in Pittsburgh made numerous arrests after a number of businesses were vandalized during protests. Authorities directed residents to stay away from the the Shadyside business district in accordance with the city's curfew.
Officials in Atlanta said they had made 52 arrests during the day, with large groups gathering at Centennial Olympic Park Drive and Marietta Street.
"We have encountered several issues during the day including instances where protesters blocked traffic on several roadways and briefly entered onto the interstate," an official said.
Other cities under curfew as of 10 p.m. include Chicago, Orlando, and Orange County, Florida.
8:52 p.m.: Protests continue across nation
Across the country, a mix of protests and lootings are continuing tonight, in spite of curfews enacted by state and city officials.
Los Angeles County, Miami-Dade County, Atlanta, Cincinnati, Seattle and Fort Worth, Texas, all entered curfews at 9 p.m. ET.
In Seattle, protesters shouted, "This is a protest not a riot," and marched peacefully through downtown during the early evening hours.
In the Philadelphia area, members of the National Guard blocked access to Upper Darby, the site of widespread looting Sunday night.
In New York City, police officers tussled with attempted looters on Fifth Avenue near Rockefeller Center.
One person was seen directing others away from police before store windows were smashed.
At least one person was arrested.
8:23 p.m.: LA shop owners arm themselves to protect stores
As Los Angeles shop owners and other businesses board up their properties from rioters, some are arming themselves.
Ahead of another night of expected protests, pawn shop owners were seen armed with AR-15s, a bail bondsman was seen with a pump action shotgun in a second-story window, and armed civilians were seen on a rooftop.
A pawn shop owner told ABC News his store has been there for 35 years and "nobody is taking it away from us."
Numerous storefronts in downtown Los Angeles, Beverley Hills, Santa Monica, Fairfax, and the San Fernando Valley are boarded up due to the rioting accompanying the protests.
8:03 p.m.: Highest ranking NYPD member takes a knee, hugs protesters
The highest-ranking uniformed member of the NYPD took a knee with protesters in Washington Square Park.
Chief of Department Terry Monahan was leading a group of officers facing off with protesters who were hurling bottles and other debris. A protest organizer tried to hold the demonstrators back but was unsuccessful.
“He tried -- we kept backing up, they kept advancing,” Monahan told ABC News.
The protester approached Monahan, who asked for the protester's megaphone so he could address the crowd. "This does not need to be riotous every single night,” Monahan told the group.
Monahan said the protest leader then asked the chief to take a knee with him for peace, and when he complied the crowd cheered.
"Have a good day, I love you," a protester said before hugging Monahan.
“I thought it was appropriate. We hugged to show there’s solidarity,” said Monahan, who added that he had never before done anything like that with a protester.
6:52 p.m.: Trump deploying thousands of 'heavily armed soldiers'
Making his first public appearance since this weekend's riots, President Trump vowed to send the military to cities around the country to quell the unrest.
Calling himself the "law and order" president, Trump said he was already deploying "heavily armed soldiers" to Washington, D.C., to ensure that violence and property destruction didn't occur as the city began its 7 p.m. curfew.
"We are putting everybody on warning -- our 7 o'clock curfew will be strictly enforced," Trump said.
Minutes before the news conference began, police cleared the area outside the White House by firing tear gas into crowds of protesters who were chanting, "No violence."
Trump cited antifa and "thugs" as the main factors behind the weekend's violence, saying they were drowning out the voices of peaceful protesters.
He said he recommended that all state and city officials deploy the National Guard and warned that if they didn't, he would deploy the military to their locations.
"Mayors and governors must establish an overwhelming law enforcement presence until the violence has been quelled," he said.
6:18 p.m.: National Guard troops deployed near White House
National Guard troops have been deployed near the White House, hours after the President Donald Trump said he wanted a show of force in the area.
Trucks with troops were seen near Lafayette Park across Pennsylvania Avenue where large groups of protesters have clashed with police for the past three nights.
A U.S. official said that active duty Army military police units from Fort Bragg, North Carolina, will be in the nation's capital tonight after days of violent protests that have included fires set not far from the White House.
5:37 p.m.: Curfew extended in nation's capital
The District of Columbia is imposing a curfew for the next two nights, Mayor Muriel Bowser announced.
The curfew will be in effect from 7 p.m.-6 a.m. on both Monday night and Tuesday night.
It will not apply to essential workers and those voting and participating in election activities, the mayor said.
5:14 p.m.: Seattle instituting another curfew
Seattle Mayor Jenny Durkin announced the city will have another curfew tonight following this weekend's protests, which she called the worst she's seen in more than 20 years.
The curfew will start at 6 p.m. PST and last until 5 a.m.
Durkin says hundreds of buildings were damaged Saturday, with more than 90 of the properties located in Chinatown International District.
4:45 p.m.: 1 dead from police shooting in Louisville, police chief fired
The Kentucky State Police will independently investigate a deadly shooting that took place overnight at the hands of police, Gov. Andy Beshear said.
Around midnight, officers with the Louisville police and the Kentucky National Guard were trying to disperse a crowd when they "were fired upon," Beshear said.
The local police and National Guard returned fire, "resulting in a death," Beshear said.
Louisville Metro Police Chief Steve Conrad has since been fired after it was announced that no body camera footage was available of the shooting, The Louisville Courier Journal reported.
Conrad previously said he would retire at the end of June after facing immense pressure following the March death of Breonna Taylor, a young black woman who was shot dead by police while in her home.
4 p.m.: NYC curfew to begin at 11 p.m.
A curfew in New York City will go into effect from 11 p.m. Monday to 5 a.m. Tuesday in the wake of violence and property damage during Sunday night's protests, the governor and mayor said.
The New York City Police Department will also double its presence.
"I stand behind the protestors and their message, but unfortunately there are people who are looking to distract and discredit this moment," New York Gov. Andrew Cuomo said in a statement. "The violence and the looting has been bad for the city, the state and this entire national movement, undermining and distracting from this righteous cause. While we encourage people to protest peacefully and make their voices heard, the safety of the general public is paramount and cannot be compromised."
Luxury retailers on Madison Avenue were seen Monday boarding up their glass storefronts and windows in anticipation of additional protests.
More than 250 people were arrested during protests overnight Sunday in New York City, which included significant looting, vandalism and theft of luxury stores in the Soho neighborhood.
Looting is rare for New York City and Mayor Bill de Blasio on Monday condemned the behavior as "unacceptable."
The NYPD believes the destruction of property, particularly at high-end retail stores, is part of a preconceived plan by agitators who have co-opted the demonstrations related to Floyd's death.
"We're seeing a lot of outside and independent agitators connected with anarchist groups who are deliberately trying to provoke acts of violence," Deputy Police Commissioner John Miller said on Sunday.
These "agitators" came prepared to commit property damage, Miller said, and directed followers to do so selectively, only in wealthier areas and at high-end stores.
More than 1,000 people have been arrested since protests began in New York City on Thursday.
One in seven protesters who have been arrested are from outside the city, the NYPD said, including states such as Massachusetts, Connecticut, Pennsylvania, Iowa, New Jersey, Nevada, Virginia, Maryland, Texas and Minnesota.
Among the 345 arrested Saturday night was the mayor's 25-year-old daughter, Chiara. She was arrested for unlawful assembly and given a desk appearance ticket, according to NYPD sources.
"I love my daughter deeply," de Blasio said Monday. "I'm proud of her that she cares so much."
"She was acting peacefully. She believes that everything she did was in the spirit of peaceful, respectful protest," de Blasio said. "I will let her speak for herself ... But I admire that she was out there trying to change something that she thought was unjust."
The NYPD overall "showed restraint" as they worked to keep the peace and allow demonstrators to continue to protest on Sunday, the mayor said.
But De Blasio did condemn what he called the rare act of officers acting inappropriately, bringing up the "troubling video" of two police cars moving through a crowd in Brooklyn Saturday night.
Video showed one police SUV being blocked by a group of protesters behind a barricade as various items and objects can be seen striking the vehicle. Another NYPD SUV then pulled up alongside the first vehicle before both of them can be seen accelerating into the crowd of people knocking many of them over as the screaming and yelling from the crowd began to intensify.
"Not acceptable," the mayor said, stressing that there's "no situation where a police vehicle should drive into a crowd of protesters or New Yorkers."
The incident is under investigation.
De Blasio also called for the officer who pulled a gun on a group of protesters to be fired.
"Any officer who does the wrong thing there needs to be consequences and they need to be fast," the mayor said.
Cuomo and de Blasio on Monday also reminded protesters to wear face coverings to protect themselves against COVID-19.
3:50 p.m.: Denver cleans up, police chief commits to marching with protesters
Hundreds of volunteers showed up in downtown Denver Monday morning to pick up trash and wash the walls and statues covered in graffiti from Sunday's massive protest.
Denver Police Chief Paul Pazen was spotted wiping away tears. He told ABC News it hurt to see the damage to the city, but it was inspiring to see the massive cleanup effort.
Pazen said he also spoke with a young, black protester, committing to march with him.
"[I told him] I would stand with him and I would do the hard work with him moving forward," Pazen said. "This is not acceptable. We cannot continue down this path. And if it means coming together and having those hard conversations, getting into some heavy lifts, then our commitment is to do that."
A curfew will be in effect in Denver from 9 p.m. to 5 a.m. each night this week until Friday morning.
3:10 p.m.: Independent autopsy says George Floyd died from asphyxia
An independent autopsy requested by Floyd's family found that he died by homicide, caused by asphyxia due to neck and back compression that led to a lack of blood flow to the brain.
The doctors conducting the independent autopsy found that the sustained pressure on the right side of Floyd's carotid artery prevented blood flow to the brain and that the weight on his back kept him from breathing.
The weight, the handcuffs and the positioning were contributory factors because they hurt Floyd's diaphragm, doctors said, adding that it appeared Floyd died at the scene.
The combined effects of being restrained, possible intoxicants in his system and underlying health issues -- including heart disease -- probably played a role in his death, doctors said. The preliminary findings reported "no physical findings that support a diagnosis of traumatic asphyxia."
Floyd's family is calling for the arrest of the three other officers at the scene and for a first-degree murder charge for Derek Chauvin, the since-fired officer who pinned Floyd to the ground.
2:30 p.m.: Total of 65 US Park Police injured during DC protests
A total of 65 U.S. Park Police were injured during three nights of protests in Washington, D.C.
Most of the injuries came from projectiles being thrown at officers; they were hit with bricks, urine bottles and petroleum-based substances, Sgt. Eduardo Delgado, spokesman for the Park Service, told ABC News.
Police arrested 88 people related to the violent demonstrations Sunday night, Metropolitan Police Chief Peter Newsham said. Of those, 44 were charged with felony rioting.
Newsham said the city is looking at federal statutes that might be used to prosecute some of those arrested.
The entire D.C. National Guard has been activated by Army Secretary Ryan McCarthy to assist U.S. Park Police, according to Master Sgt. Craig Clapper, a spokesman for the D.C. National Guard.
The additional forces will be unarmed and in a support role to U.S. Park police and that they will be equipped in protective riot gear, Clapper said.
Mayor Muriel Bowser has ordered a two-day curfew, beginning at 7 p.m. Monday.
Newsham warned, if you are not a member of the media or performing an essential function, "local and federal police will take you into custody."
1:48 p.m.: More than 400 arrested in Santa Monica
In Santa Monica, California, more than 400 people were arrested on Sunday.
Charges included looting, violating curfew, burglary and assault with a deadly weapon, officials said.
While there were no serious injuries, Santa Monica Police Chief Cynthia Renaud on Monday cautioned protesters that the looters "are opportunists" who will "take advantage" of the peaceful protests.
She said they "are tracking where peaceful protests are occurring, and they are then going to that city knowing that resources will be tied up ensuring first amendment rights to free speech. And they take advantage of that, and they loot and they perform criminal activity."
1:20 p.m.: More National Guardsmen on duty now than ever before
Between the George Floyd protests and the COVID-19 pandemic, there are more National Guardsmen on duty right now for a domestic response than ever before, the National Guard Bureau said.
There are now 66,700 activated National Guard soldiers and airmen. To put that in context, for Hurricane Katrina in 2005, more than 51,000 were activated.
The National Guard is now active in the District of Columbia and at least 25 states: Alabama, Arizona, California, Colorado, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, North Carolina, North Dakota, Nevada, Ohio, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, Washington state and Wisconsin.
New York Gov. Andrew Cuomo said the National Guard is on standby but not needed in New York City at this time because the NYPD is such a large police force.
1 p.m.: 'Miraculous' that no one injured when truck barreled toward Minnesota crowd
In Minneapolis -- the epicenter of the protests -- a memorial will be held for George Floyd on Thursday, Gov. Tim Walz said
Some of the Minnesota National Guard will be redeployed and sent home, he said.
On Sunday afternoon, between 5,000 and 7,000 people joined in a "very peaceful demonstration" at Minneapolis' U.S. Bank Stadium, said DPS Commissioner John Harrington.
Then the group moved to the freeway, and that was when a tanker truck started barreling toward the crowd.
Harrington called it "miraculous" that there were no deaths or injuries.
Walz also commended the peaceful protesters who jumped in to protect the truck driver, even though at the time the driver appeared poised to assault them.
It does not appear that the truck driver headed toward the protesters intentionally, Harrington said.
"He saw the crowd and initially, what it looks like, he panicked, and he just kept barreling forward," Harrington said. "And then he saw ... a young woman on a bike fall down in front of him and he slammed on the brakes. And he slid for a certain period of time until the vehicle stopped."
The driver is facing assault charges.
12 p.m.: Nearly 700 arrested in Chicago
Just on Sunday, 699 people were arrested in Chicago, primarily for looting, David Brown, superintendent of the Chicago Police, said Monday.
Brown addressed the rioters and looters directly, saying, "you disgraced the name of Mr. Floyd by your actions."
"Hate can never drive out hate," Brown said, and he vowed, "we will hold you accountable."
Brown also addressed the late George Floyd directly, saying, "We are embarrassed by the cops in Minneapolis' use of force, asphyxiating you on the streets."
"We stand with Mr. Floyd's family," he said.
11:38 a.m. Barr sending riot teams to Miami, DC
A senior Department of Justice official says U.S. Attorney General William Barr has directed the Bureau of Prisons to send riot teams (Special Operation Response Teams) to Miami and Washington, D.C. to help with crowd control, a senior DOJ official said.
The team was already present in Miami over the weekend, this official said.
On Sunday night, Barr also dispatched the FBI's Hostage Rescue Team to help D.C. police.
All FBI field offices have been instructed to set up command posts to deal specifically with the protests in nearby communities, the official said.
10:24 a.m.: Minnesota AG 'seriously looking' at prosecuting other officers
Minnesota Attorney General Keith Ellison said on SiriusXM's "The Joe Madison Show" on Monday that he's "very seriously looking at" prosecuting the three other officers who were at the scene of Floyd's death.
"I'm not prepared to announce anything at this moment," Ellison said, adding, "I will say that we are going to hold everybody accountable for what they did wrong and what they did that's illegal."
"We are reviewing the video tapes, the audio tapes, all the evidence, and we will make a charging decision based on the facts that we can prove," he said.
Hennepin County Attorney Mike Freeman said Sunday that he has asked Ellison to help with the case.
At a Sunday night news conference Ellison said he wanted to give people "a dose of reality."
"Prosecuting police officers for misconduct is very difficult," Ellison said. "We are pursing justice relentlessly and we are pursuing it on behalf of the people of Minnesota."
9:13 a.m.: Miami-Dade County mayor wants to honor protesters who stopped potential looters
In Miami, video overnight showed a group of protesters shattering the glass door of a CVS as they prepared to loot the store -- only to be stopped by a group of peaceful protesters who formed a line to prevent them from entering. Police then arrived and dispersed the crowd.
Monday morning, Miami-Dade County Mayor Carlos Gimenez said he wants to meet and commend the protesters who kept the potential looters from breaking in.
"Anyone who can identify the people responsible for keeping the peace as they, themselves, properly exercised their right to assemble and protest, please reach out to the Mayor's office via social media on the Mayor's Facebook page Mayor Carlos A. Gimenez, or on Twitter @mayorgimenez," he said in a statement.
2:22 a.m.: Derek Chauvin moved to state prison in Oak Park Heights, Minnesota
Derek Chauvin, the officer accused of killing George Floyd, is now in custody at the state prison in Oak Park Heights, Minnesota, said Minnesota Department of Corrections Commissioner Paul Schnell.
Hennepin County Sheriff David Hutchison made the request to move him over concerns about the large number of people who could possibly be booked into Hennepin County Jail Sunday night, and concerns over COVID-19.
Chauvin's court date has been pushed back a week to June 8.
ABC's Ryan Burrow reports for ABC News Radio:
1:40 a.m.: In several cities, protesters and police share a hug
Although Sunday's protests included much of the looting and violence of the previous week's demonstrations, there were signs throughout the country that relations between protesters and police were warming.
In Orlando, Florida, photos on social media showed two police officers holding hands with protesters through a barricade.
Video showed a Florida Highway Patrol trooper in Miami detach himself from a security line to offer a hug to a woman sitting on a motor scooter, who said, "I appreciate your patience" after troopers remained calm when protesters approached them.
In New York City's Foley Square, a cheer went up among protesters when a group of NYPD officers took a knee in a show of solidarity.
In Oklahoma City, cameras also captured sheriff's deputies taking a knee, with some hugging protesters near the Oklahoma County Jail.
In Flint, Michigan, video showed Genesee County Sheriff Chris Swanson telling a crowd of protesters that he'd ordered his deputies to lower their batons and that he wanted to make the event "a parade, not a protest." The crowd then applauded the sheriff and invited him to join the march.
12:41 a.m.: Clashes continue in some cities, while others are more calm
Arrests during Sunday's protests have driven the total number of demonstrator arrests to 4,100 since protests began early in the week, according to the AP.
Confrontations between police and protesters continued for another night in Brooklyn, where demonstrators clashed with officers outside Barclay's Center.
In Boston, an SUV drove through a crowd of protesters but officials said no one appeared to be seriously hurt.
In Washington, D.C., members of the U.S. Marshals Service and DEA agents were called in to assist National Guard troops responding to protests near the White House, a Department of Justice official said.
In Atlanta, two police officers were fired for using excessive force during an arrest of two college students during Saturday night's protests. Video of the incident appeared to show officers Tase the two students as they sat in their vehicle, and then forcefully drag them out of the car.
Other protests were peaceful. Minnesota Gov. Tim Walz said demonstrators were "largely cooperative."
ABC News' Luis Martinez, Whitney Lloyd, Will Gretzky, Aaron Katersky, Stephanie Wash, Victor Oquendo, Dee Carden, Jeff Cook, Matt Foster, Alexander Mallin, Matt Zarrell, Matthew Fuhrman, Josh Einiger and Marc Nathanson contributed to this report.