Four people are dead and 52 people have been arrested after Donald Trump supporters stormed a session of Congress held Wednesday to certify Joe Biden's election win, triggering unprecedented chaos and violence at the heart of American democracy.
Moments after an extraordinary rally by Mr Trump seeking to overturn the election, a flag-waving mob broke down barricades outside the Capitol and swarmed inside, rampaging through offices and onto the usually solemn legislative floors.
Washington, DC, Police Chief Robert Contee said four people had died on Capitol grounds on Wednesday, including a woman who was shot by police.
She was shot as the mob tried to break through a barricaded door where police were armed on the other side, and later died in hospital.
The police chief said the other three people died in medical emergencies.
As rioters gained access to the Capitol, one Trump supporter in jeans and a baseball cap was pictured propping a leg up on House Speaker Nancy Pelosi's desk, where a threatening note had been left saying 'WE WILL NOT BACK DOWN'.
Videos posted online showed protesters breaking windows and police deploying teargas inside the building, with the National Guard also called in over the unrest.
A Trump supporter sits at the desk of US House Speaker Nancy Pelosi Source: EPA
The note left on the desk of House Speaker Nancy Pelosi Source: EPA
The Senate has since reconvened and resumed the process of certifying Mr Biden's election win.
Of the 52 arrests, the police chief said 47 related to violations of a 6pm curfew ordered by Washington Mayor Muriel Bowser, with 26 of those involving people arrested on US Capitol grounds.
Several others were arrested on charges related to carrying unlicensed or prohibited firearms.
In addition, he said two pipe bombs were recovered from the headquarters of the Republican and Democratic national committees, as well as a cooler from a vehicle on US Capitol grounds that contained Molotov cocktails.
As the incident unfolded on Wednesday, some US politicians described it as a "coup".
"A mob storming the US Capitol to overturn an election. A coup in progress," said representative Val Demings in a tweet.
"This is anarchy. This is an attempted coup. And it's happening in America because of lawless lawmakers," added another congressman, Seth Moulton.
"The president is inciting domestic terrorism," said representative Mark Pocan.
People shelter in the House gallery as protesters try to break into the House chamber Source: AP
After his supporters entered the building, Mr Trump posted a series of social media messages.
Across various tweets, he told the demonstrators to "go home in peace", described them as "very special" and said "these are the things and events that happen when a sacred landslide election victory is so unceremoniously & viciously stripped away from great patriots".
Facebook, Twitter and YouTube have removed various posts from Mr Trump's accounts. Facebook later barred Mr Trump from posting over messages it said were promoting violence - following a similar stand taken by Twitter.
He had earlier used a rally to warn "weak" Republicans not to certify Mr Biden's victory and put direct pressure on Vice President Mike Pence, who later confirmed he would not intervene.
In response to the situation, Mr Biden said for demonstrators to storm the Capitol, smash windows, occupy offices, invade the halls of Congress and threaten the safety of duly elected officials: "It's not a protest, it's insurrection."
He said it was an "unprecedented assault" on US democracy.
"The scenes of the chaos at the Capitol do not reflect a true America, do not represent who we are. What we're seeing are a small number of extremists dedicated to lawlessness," he said.
"I call on this mob to pull back and allow the work of democracy to go forward."
Mr Biden won more than seven million votes more than Mr Trump in the 3 November election and leads him 306-232 in the state-by-state Electoral College that determines elections.
Mr Trump has repeatedly alleged without evidence that there was vote-rigging but his team has not been able to prove a single case in court.
Additional reporting by AAP, AFP Reuters.
