Violence erupted in several parts of Washington following a “Stop the Steal” rally in support of repeated and baseless allegations of Mr. Trump’s election fraud.
Thousands of Trump supporters marched downtown on Saturday afternoon to falsely claim that President-elect Joe Biden stole the 2020 presidential election.
Tensions began to boil as darkness fell, with brawls and brawls breaking out in several streets of the capital.
Video and footage of the clashes show members of the far-right group, Proud Boys, clashes with left-wing Antifa activists late into the night.
Four people were rushed to hospital with stab wounds, DC Fire Department spokesman Doug Buchanan said.
Their injuries were described as serious, but not fatal. Authorities said 23 people had been arrested.
Meanwhile, law enforcement declared a riot in Olympia, Washington, where one person was shot dead. The suspect has been arrested, the Washington State Patrol said.
The condition of the gunshot victim was not immediately clear. Four arrests were made in total and four officers injured, the force added.
Violence erupted just a day after the incumbent president suffered a Supreme Court defeat, further undermining his desperate attempt to retain the White House.
Judges on Friday dismissed a lawsuit filed by the state of Texas asking them to reject election results in four key battlefield states where Mr. Trump lost to Mr. Biden.
Protests erupted in several state capitals following the decision.
The mostly unmasked rallies of Trump worshipers were conceived as a show of force just two days before the electoral college convened to formally elect Mr. Biden as the 46th president.
Mr Trump, whose term ends Jan. 20, refuses to concede while clinging to baseless allegations of electoral fraud.
The defeated outgoing tweeted his apparent surprise Saturday morning at the rallies, publicly known for weeks: “Wow! Thousands of people are forming in Washington (DC) for Stop the Steal. I didn’t know about it, but I’ll see them! #MAGA “.
He left the White House around noon to attend the Army-Navy football game at the US Military Academy in West Point, New York. As the Marine One helicopter passed over a rally on the National Mall, cheers rose.
Michael Flynn, the former national security adviser recently pardoned by Mr Trump, was speaking from the stage at the time.
“It’s pretty cool. Just imagine being able to jump in a helicopter and take a joyous ride around Washington, ”said Mr. Flynn, whose pardon erased his conviction for lying to the FBI twice during the Russia investigation.