The two victims died from their injuries, according to the Kenosha Police Department. A third gunshot victim was taken to a hospital with "serious, but non-life-threatening injuries," police said.
Cellphone video from Tuesday night's protests showed a white man, armed with a semiautomatic rifle, running past police and being chased by demonstrators. The footage showed the man trip and fall and appear to open fire on protesters. He then is seen running away.
The alleged gunman, identified as 17-year-old Kyle Rittenhouse of Illinois, surrendered to authorities in Antioch, Illinois, before dawn Wednesday, according to Antioch Interim Police Chief Geoff Guttschow. Rittenhouse was arrested based on a warrant issued by authorities in Wisconsin's Kenosha County, charging him with first-degree intentional homicide. He's also being held on a charge of "fugitive from justice," for purposes of extradition to Wisconsin, Guttschow said.
Charges against Rittenhouse were officially filed in Wisconsin on Thursday, and included two homicide counts and one attempted homicide count. Rittenhouse was also charged with two counts of recklessly endangering safety and possession of a dangerous weapon by a juvenile.
A criminal complaint filed Thursday identified the two people killed as Joseph Rosenbaum and Anthony Huber, and the injured victim as Gaige Grosskreutz.
Rosenbaum followed Rittenhouse and threw a plastic bag at him in the parking lot of the auto repair shop Car Source Auto Service, according to the complaint. Based on a video prosecutors reviewed, Rosenbaum approached Rittenhouse following a loud bang. After four more bangs, Rosenbaum fell to the ground. After allegedly shooting Rosenbaum, Rittenhouse made a phone call and said, "I just killed somebody," the complaint said. An autopsy found that Rosenbaum was shot five times -- in the right groin, back, left hand, left thigh and right side of his forehead, according to the complaint.
Rittenhouse was then chased by protestors and fell, according to the complaint. At that point, Huber tried to pull Rittenhouse's gun away when he was allegedly shot and killed, according to the complaint. Rittenhouse then allegedly shot Grosskreutz, who had his hands in the air, in the right arm, according to the complaint.
Huber's autopsy showed he had a gunshot wound to his chest that perforated his heart, aorta, pulmonary artery and right lung, the complaint said.
The long gun allegedly used in the shootings was a Smith & Wesson AR-15 style, .223 rifle, court records show.
The Bureau of Alcohol, Tobacco, Firearms and Explosives is assisting in tracing a firearm recovered Wednesday that is believed to have been used in Tuesday night's shooting, a law enforcement official told ABC News.
The social media accounts were deactivated Wednesday and are now part of the investigation into the deadly shooting. Investigators are looking to determine whether the accounts are legitimate and are scrubbing them for any information pertinent to the probe, two law enforcement officials told ABC News.
Local law enforcement agencies are not commenting on the social media accounts.
Trump's reelection campaign issued a statement Wednesday night distancing itself from the alleged shooter.
"President Trump has repeatedly and consistently condemned all forms of violence and believes we must protect all Americans from chaos and lawlessness," Tim Murtaugh, communications director for the Trump 2020 campaign, said in a statement. "This individual had nothing to do with our campaign and we fully support our fantastic law enforcement for their swift action in this case."
Rittenhouse is currently being held at the Lake County Juvenile Detention Center in Vernon Hills, Illinois, according to Guttschow.
Antioch Fire Chief Jon Cokefair confirmed to ABC News that Rittenhouse was a cadet with his fire department from September 2018 to March 2020. The Grayslake Police Department in Illinois has also confirmed to ABC News that a former public safety cadet from its youth program is a suspect in the Kenosha protest shootings.
Attorney John Pierce of Los Angeles told ABC News that he has been retained to represent Rittenhouse.
"We will obtain justice for Kyle," said Pierce, adding he was headed to Wisconsin Thursday night to meet with his client's family and appear at Rittenhouse's bail hearing on Friday.
Pierce said he has established a legal defense fund for Rittenhouse through a Texas 501(c)(4) nonprofit called #FightBack Foundation Inc. that was formed by him and Georgia attorney L. Lin Wood.
"That will be the sole authorized vehicle to fund Kyle's defense," he said.
The civil unrest in Kenosha unfolded Sunday evening after Blake was shot by police in broad daylight. Cellphone video taken by a witness shows three Kenosha police officers following Blake around his SUV, and at least one of them is seen shooting Blake multiple times in the back as he opened the driver's side door and entered the vehicle, where his three young children were still inside.
The officers involved in the shooting have been placed on administrative leave, according to the Wisconsin Department of Justice's Division of Criminal Investigation, which is leading the probe into the incident. The Kenosha Police Department does not have body cameras.
Authorities, in a statement, later said that officers attempted to stop Blake with a stun gun but that efforts were unsuccessful.
Since then, hundreds of protesters have converged at the Kenosha Police Department headquarters and the Kenosha County Courthouse. Some have smashed patrol car windows and set fires to buildings. Police in riot gear have repeatedly deployed tear gas, flash bangs and rubber bullets to disperse the crowds.
The violence prompted Trump and Wisconsin Gov. Tony Evers to mobilize additional members of the National Guard to Kenosha.
Blake's family has repeatedly called for peaceful protests.
A statement released Wednesday night by the Wisconsin Department of Justice identified the officer who shot Blake and provided more details on the incident.
Officers from the Kenosha Police Department were dispatched to a residence Sunday, after a female caller reported that her boyfriend was there and "was not supposed to be on the premises," according to the statement. During the incident, the officers tried to arrest Blake and deployed a stun gun in an attempt to stop him, but "the taser was not successful," according to the statement.
Blake then walked around his car, opened the driver's side door and "leaned forward," according to the statement. Officer Rusten Sheskey, who has been with the Kenosha Police Department for seven years, fired his gun seven times into Blake's back while holding onto his shirt, according to the statement. No other officer fired their weapon, the statement said.
The officers "immediately provided medical aid" to Blake, who was then flown to a hospital in Milwaukee, according to the statement.
During the investigation following the initial incident, Blake "admitted that he had a knife in his possession," according to the statement. Investigators recovered a knife from the driver's side floorboard of Blake's vehicle. No additional weapons were found, according to the statement.
When taking questions from reporters at a press conference Wednesday night, Wisconsin Department of Justice officials would not say whether Blake was the person who the female caller said was at her home.
Prominent civil rights attorney Benjamin Crump, who is representing Blake's family, said his client was attempting to de-escalate a domestic incident when police drew their pistols and stun guns on him. Crump said Blake was walking away to check on his children when police shot him.
He told ABC News that Blake's family is calling for the officers involved in the shooting to be terminated from the police force and charged with attempted murder.
"Where is humanity? Where is the professionalism? Where is the training? Why is it again that we're seeing another African American who the police are supposed to protect and serve like anybody else use this brutal, excessive force?" Crump said. "It was done in front of his three little boys … who were all sitting in the car. Eight years old, five years old, three years old. Can you imagine the psychological issues these babies are going to have?"
Blake's family told ABC News he is currently paralyzed from the waist down but that doctors hope the paralysis is temporary.
Blake is handcuffed to his hospital bed, his father, Jacob Blake Sr., told ABC News. A warrant was issued on July 7 for Blake's arrest on sexual assault and domestic abuse charges, yet it is unclear at this time if that is why he is handcuffed.
Despite his condition, Blake has been the one trying to comfort family.
"That tells you what kind of man he is," Blake's uncle told ABC News in an interview that aired Wednesday on "Good Morning America."
ABC News' Andy Fies, Sabina Ghebremedhin, Whitney Lloyd, Will Steakin and Jim Vojtech contributed to this report.