Hundreds of President Donald Trump's supporters stormed the U.S. Capitol on Wednesday in a stunning bid to overturn his election defeat, battling police in the hallways and delaying the certification of Democratic President-elect Joe Biden's victory for hours.

Police said four people died during the chaos - one from gunshot wounds and three from medical emergencies - and 52 people were arrested.

Some besieged the House of Representatives chamber while lawmakers were inside, banging on its doors and forcing suspension of the certification debate. Security officers piled furniture against the chamber's door and drew their pistols before helping lawmakers and others escape. 

Hours later, both houses of Congress resumed their work on certifying Biden's Electoral College win, with debate stretching into the early hours of Thursday.

Follow the latest updates in our LiveBlog.

Joe Biden and some former U.S. presidents expressed shock and outrage at the assault on the symbol of American democracy.

On national television, Biden said the invasion of the Congress is not a protest but an "insurrection," and urged Trump to demand "an end to this siege."

Former Republican President George W. Bush said he was appalled by the "reckless behavior of some political leaders since the election."

"It is a sickening and heartbreaking sight," Bush said in a statement. He said the violent assault on the Capitol was undertaken by "people whose passions have been inflamed by falsehoods and false hopes. Insurrection could do grave damage to our nation and reputation."

Multiple Democratic Congressional representatives have announced they will try to impeach President Donald Trump. U.S. Representative Ilhan Omar said she was drawing up articles of impeachment to call for Trump's removal from office.

Read more:

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How the world is reacting to pro-Trump mob storming U.S. Capitol

Meanwhile, the sitting-President was twittering in defense of the actions of his supporters while calling on them to "go home with love & in peace."

"These are the things and events that happen when a sacred landslide election victory is so unceremoniously & viciously stripped away," he tweeted.

Trump concluded the tweet, rather stunningly, with "Remember this day forever!" 

Twitter later said that future violations of the social media platform's rules, including its "Civic Integrity" or "Violent Threats" policies, will result in permanent suspension of the @realDonaldTrump account.

Twitter has restricted users from retweeting the video "due to a risk of violence," as hundreds of protesters sought to force Congress to undo the president's election loss to Joe Biden. 

Social media companies have been under pressure to police misinformation on their platforms around the election. Trump and his allies have continuously spread unsubstantiated claims of election fraud that have proliferated online.

Facebook and Alphabet's YouTube took down a video from President Donald Trump on Wednesday that continued to make the baseless claim the election was fraudulent as he told protesters who had stormed the U.S. Capitol to go home.

Facebook's vice president of integrity Guy Rosen tweeted the social media company believed the video "contributes to rather than diminishes the risk of ongoing violence," saying the action was part of "appropriate emergency measures."

YouTube said the video violated its policy against content that alleges "widespread fraud or errors changed the outcome of the 2020 U.S. Election." YouTube spokesperson Farshad Shadloo added the company does allow copies that include additional context.

In a statement on Wednesday, the Anti-Defamation League called for social media companies to suspend Trump's accounts, saying the events at the Capitol resulted from "fear and disinformation that has been spewed directly from the Oval Office."

Former Facebook security chief Alex Stamos tweeted: "Twitter and Facebook have to cut him off. There are no legitimate equities left and labeling won't do it." 

According to researchers and public postings, violent rhetoric and advice on weaponry ramped up significantly in the past three weeks on many social media platforms as multiple groups planned rallies for Wednesday, including Trump supporters, white nationalists and enthusiasts of the wide-ranging conspiracy theory QAnon.

'Assault on U.S. democracy'

The surge through the halls of Congress in shocking scenes broadcast across the globe was condemned by world leaders.

UN Secretary-General Antonio Guterres, according to his spokesperson Stephane Dujarric, was "saddened" by the breach of the U.S. Capitol building by supporters of Trump.  

The EU's foreign policy chief called it an "assault on U.S. democracy."

"In the eyes of the world, American democracy tonight appears under siege," the official, Josep Borrell, tweeted. "This is an unseen assault on U.S. democracy, its institutions and the rule of law. This is not America. The election results of November 3 must be fully respected." 

British Prime Minister Boris Johnson also condemned the "disgraceful scenes," as Ireland's government attacked the outgoing president for his "assault" on democracy. 

"Disgraceful scenes in U.S. Congress. The United States stands for democracy around the world and it is now vital that there should be a peaceful and orderly transfer of power," Johnson said on Twitter. 

British Foreign Secretary Dominic Raab added in his own tweet: "The U.S. rightly takes great pride in its democracy, and there can be no justification for these violent attempts to frustrate the lawful and proper transition of power." 

Irish Premier Micheal Martin, who has invited the Irish-American Biden to visit his ancestral homeland early in his presidency, tweeted his condemnation. "The Irish people have a deep connection with the United States of America, built up over many generations. I know that many, like me, will be watching the scenes unfolding in Washington D.C. with great concern and dismay," Martin said. 

Irish Foreign Minister Simon Coveney went further in directly rebuking Trump. "Shocking & deeply sad scenes in Washington, D.C. -- we must call this out for what it is: a deliberate assault on Democracy by a sitting President & his supporters, attempting to overturn a free & fair election!" he tweeted. "The world is watching! We hope for restoration of calm."

French Foreign Minister Jean-Yves Le Drian condemned "a serious attack on democracy."

"The violence against American institutions are a serious attack on democracy. I condemn it," Le Drian tweeted. "The will and the votes of the American people must be respected."

(Cover photo: Violent protesters storm the U.S. Capitol, in Washington, D.C., U.S., January 6, 2021. /AP)

(With input from agencies)