President Joe Biden has paid tribute to the US Capitol police officer who died after responding to pro-Trump rioters who attacked the building on Wednesday 6 January.
Brain Sicknick was hurt as he “physically engaged” with the violent mob, the police said.
The police officer became the fifth victim of the riots.
Mr Biden arrived on Tuesday (2 February) night at the Capitol, where the officer's remains are lying in honour in the building's famous Rotunda, to pay his respects.
Here’s everything you need to know about Brian Sicknick’s death - and who else was killed during the violent attack.
What happened to Brian Sicknick?
The US Capitol building in Washington DC was overwhelmed by mobs of pro-Trump supporters, as Congress met on Wednesday 6 January to certify Joe Biden’s presidential win.
The violence came hours after Trump himself encouraged his followers to fight against the election results, which he has consistently claimed to be “fraudulent”.
His supporters fought past police officers to storm the Capitol building, forcing Congress to halt the certification process.
During the violent clashes, Brian Sicknick, a US Capitol police officer, was “hit over the head with a fire extinguisher” by a rioter, two sources told The New York Times.
Sicknick returned to his division office where he then collapsed, before being taken to a nearby hospital where he was put on life support, according to US Capitol Police.
He then died of his injuries at around 9:30pm on Thursday 7 January, the department said.
Sicknick joined the Capitol Police in July 2008.
US Capitol Police said: "The death of Officer Sicknick will be investigated by the Metropolitan Police Department’s Homicide Branch, the USCP, and our federal partners.
"Officer Sicknick joined the USCP in July 2008, and most recently served in the Department’s First Responder’s Unit.
"The entire USCP Department expresses its deepest sympathies to Officer Sicknick’s family and friends on their loss, and mourns the loss of a friend and colleague."
Who else died in the riots?
Four other people were fatally injured in the chaos that unfolded at the Capitol building.
They were all pro-Trump supporters who attended the riot: Ashli Babbitt, 35, Roseanne Boyland, 34, Kevin Greeson, 55, and Benjamin Phillips, 50.
Babbitt, an Air Force veteran, was shot by a Capitol police officer.
Police have said Boyland may have been crushed in the mob, while Greeson, who had high blood pressure, suffered from a heart attack and collapsed.
Phillips had a “medical emergency”, according to police reports.
Fourteen officers are confirmed to have been injured in the riot.
The police have been heavily criticised after the violet mob was able to break into the Capitol building.
President-elect Joe Biden has since condemned the lack of action, saying: "Nobody could tell me that if it was a group of Black Lives Matter protesters yesterday they wouldn't have been treated very differently than the thugs that stormed the Capitol."
Who was Ashli Babbitt?
The woman who was shot and killed during the skirmish was identified as Ashli Babbitt, according to local news reports.
Fox 5 DC first identified Babbitt, and said the 14-year US Air Force veteran from San Diego was struck by a bullet after she entered the Capitol building’s legislative complex with rioters.
She was later pronounced dead after being transported to a local hospital in critical condition.
Robert Contee, Washington DC’s Chief of Police, later confirmed that a woman was shot by a Capitol police officer as she attempted to climb into the building through a window.
The officer who fired the shot has been placed on administrative leave while an investigation is conducted.
“I really don’t know why she decided to do this,” her mother-in-law told Fox 5, as Babbitt’s husband – who did not travel with his wife to DC – called her “a patriot and strong supporter of Donald Trump.”
Just hours before the violence, Babbitt tweeted: “Nothing will stop us… they can try and try and try but the storm is here and it is descending upon DC in less than 24 hours… dark to light!”