A US Capitol police officer has died of injuries suffered during a riot led by supporters of President Donald Trump, the force said.
Wednesday's breach of the government building was a stunning assault on American democracy at a time when Congress was certifying the victory of President-elect Joe Biden.
CNN had initially reported that an unnamed officer had become the fifth person to die as a result of the day's violence, but police later denied it.
However they have now confirmed that Brian D. Sicknick has died after he collapsed at the station, having suffered injuries in clashes with protesters.
"Officer Sicknick was responding to the riots...and was injured while physically engaging with protesters," police said in a statement.
He succumbed on Thursday after being taken to hospital following his collapse upon returning to his divisional office, they added.
Metropolitan homicide officials will investigate the death of Sicknick, who joined the U.S. Capitol Police in 2008, along with the USCP and its federal partners, police said.
Four other people died in the storming of the US Capitol, including US Air Force veteran Ashli Babbit, who was shot dead by police.
The 35-year-old was part of a crowd that breached the building, allegedly ignoring officers' calls to move back.
Fellow Trump fanatics Kevin Greeson, Benjamin Phillips and Roseanne Boyland all died due to "medical reasons" while involved in the riots.
Trump last night condemned the violence in an abrupt change of course, saying rioters had "defiled" the seat of American democracy and must be held accountable.
The President released a video to Twitter in which he also accepted the result of the election for the first time and pledged a "smooth transition" of power to Joe Biden.
He had been temporarily banned from Twitter and Facebook after his posts amid the chaos, after the platforms deemed his continued election denials to be inciting violence.
Democrats have been circling today, saying Trump must be ousted from the White House before January 20, when Biden will be inaugurated.
It is thought Vice-President Mike Pence is against invoking the 25th amendment, which allows the President to be removed from office is he is unfit to lead.
But Chuck Schumer and Nancy Pelosi, key Democrat figures in Congress, have said he should be impeached.
They have argued tonight that he still "poses a danger" and "incited an insurrection".
Yesterday, hundreds of Trump fanatics stormed the US Capitol, vandalising offices and property.
The President had earlier spoken at a rally where he encouraged followers to march on the Capitol, where Senators were ratifying the result of last year's election.
