In Washington, D.C., four people were stabbed as violence escalated Saturday night following competing protests during the day. The president's supporters, including the far-right Proud Boys, had gathered in the afternoon to denounce the results of the 2020 election -- baselessly decried as fraudulent for weeks by Trump.
Meanwhile, across the country in Olympia, Washington, a person was shot during similar protests on Saturday.
A person was taken into custody there.
Dozens arrested, 9 hurt at protests in nation's capital
The Washington, D.C., Fire Department and EMS confirmed to ABC News that as of 7 p.m. Saturday, at least nine patients -- including four stabbing victims -- were transported to area hospitals with injuries connected to demonstrations in the District.
The stabbings took place in the area of 11th Street Northwest and F Street Northwest, about four blocks west of the White House. All four patients are in critical condition, officials said.
Two police officers were also taken to the hospital with non-life-threatening injuries.
In addition, the D.C. mayor's office said at least 23 people have been arrested as of 9 p.m.
Those arrests included 10 for simple assault, six for assaults on a police officer, four for riotous acts, two for crossing a police line and one for possession of a prohibited weapon (a stun gun).
Thousands of people had gathered earlier in the day to support the president, even as courts across the country continue to toss out election-related suits, admonishing Trump's lawyers for a lack of evidence of the fraud as he has repeatedly claimed. The U.S. Supreme Court denied a lawsuit the president had claimed was "perhaps the most important case in history" on Friday.
Among the supporters of Trump appearing with protesters Saturday were Michael Flynn, the president's former national security adviser, and Roger Stone, a longtime friend and adviser. Flynn was recently pardoned by the president while Stone's conviction for lying to the House Intelligence Committee was commuted by Trump.
Shooter opens fire during Olympia protests
One person was shot and another was detained during violent protests in Olympia, Washington on Saturday afternoon, according to Washington State Patrol.
The condition of the shooting victim was not known.
"There have been sporadic confrontations throughout the day. WSP and partner agencies are working together coordinating response to the situation," Washington State Patrol said in a statement on Twitter.
The shooting took place at about 2 to 3 p.m., according to Washington State Patrol Sgt. Darren Wright. It was not known whether the shooter was part of the assembled protesters, or on what side.
People could be seen scrambling to hide behind cars and bushes following the gunfire.
Authorities declared the competing gatherings taking place at the state capital a riot at about 1:30 p.m. local time and began to disperse protesters.
There had been sporadic clashes between the groups throughout the day, with some protesters carrying guns and others spraying mace at the opposing side.
Washington State Patrol also said its bomb squad detonated a "reported IED," which was determined to be a large commercial firework. It had been lit and tossed at protesters, but did not go off.
"Had the device detonated, it could have caused significant injury," police said.
Washington State Patrol, the Olympia Police Department and Thurston County Sheriff all were in attendance at the demonstrations.
A 27-year-old pro-Trump protester was arrested last Saturday near the Capitol for firing a gun at opposing demonstrators, according to Seattle ABC affiliate KOMO. He was charged with first- and second-degree assault.
Shootings have become somewhat commonplace at protests in recent months, including multiple incidents that resulted in fatalities. Two people were killed in related shootings during a protest in Kenosha, Wisconsin, in late August, while one person was killed during a protest in Denver in October.
ABC News' Timmy Truong and Ben Siu contributed to this report.