President Trump has spoken for the first time since the violence by his supporters in the Capitol in Washington.
He distanced himself from what he called "the heinous attack", saying he had called in the National Guard "to secure the building and expel the intruders".
"Like all Americans, I am outraged by the violence, lawlessness and mayhem," he said.
"This is and must always be a nation of law and order. The demonstrators who infiltrated the Capitol have defiled the seat of American democracy. To those who engaged in the acts of violence and destruction, you do not represent our country."
In a marked change of tone from his harsh rhetoric over the past weeks, he said: "Now Congress has certified the results a new administration will be inaugurated on January 20. My focus now turns to ensuring a smooth, orderly and seamless transition of power. This moment calls for healing and reconciliation."
Mr Trump's more conciliatory tone comes as pressure rises on him.
Formerly loyal colleagues resigned and one of his most ardent media supporters was harsh in its condemnation as calls for the President's removal from office got louder.
The Wall Street Journal, a bastion of conservatives America and Rupert Murdoch's flagship newspaper in the United States turned on Mr Trump, declaring his behaviour "impeachable".
"If Mr. Trump wants to avoid a second impeachment, his best path would be to take personal responsibility and resign," its editorial said.
"It is best for everyone, himself included, if he goes away quietly."
Education Secretary Betsy DeVos and Transportation Secretary Elaine Chao both resigned.
Ms DeVos said in her resignation letter: "We are left to clean up the mess caused by violent protesters overrunning the U.S. Capitol in an attempt to undermine the people's business."
"That behavior was unconscionable for our country," she said. "There is no mistaking the impact your rhetoric had on the situation, and it is the inflection point for me."
Here's a summary of other developments:
The police have started charging rioters with a string of offences, including attacking an officer and having a loaded gun.
Washington's police said they had charged 70 people at the riot and another 44 people later.
According to The New York Times, one rioter punched a police officer repeatedly in the head and chest and then "spontaneously apologized".
According to National Public Radio: "The United States Capitol Police have identified the woman who was shot and killed by one of their officers during the pro-Trump rioting as Ashli E. Babbitt, an Air Force veteran from the San Diego area.
"Babbitt, 35, was one of four people who died during Wednesday's chaotic events, according to Washington's Metropolitan Police Department (MPD). MPD Police Chief Robert Contee said the three others who died experienced unspecified "medical emergencies."
After the interruption by rioters, lawmakers resumed and completed the affirmation of Joe Biden and Kamala Harris as President and Vice President.
Mr Biden has started naming his choices for his cabinet.
Removal from office?
Senior Democrats want Mr Trump removed from office before his due date of departure on January 20.
The Speaker of the House of Representatives Nancy Pelosi of California and Senator Chuck Schumer have called on Vice President Mike Pence to invoke the 25th Amendment to the Constitution.
The Amendment says that if a president becomes unable to do his or her job, the vice president becomes the president or acting president.
The Democrats argue that Mr Trump has become divorced from reality.
Speaker Pelosi said: "While it's only 13 days left, any day can be a horror show for America."
Democrats are also saying that if Mr Pence declines to act as they want him to, they might put Mr Trump on trial again (impeach him).
Either course would be massively divisive.
The 25th Amendment would be difficult to invoke successfully. It would involve Mr Pence writing that Mr Trump "is unable to discharge the powers and duties of his office".
This would strip Mr Trump of his powers but Mr Trump could write another letter saying he was capable of exercising his powers, and that would allow him to resume his role.
There would then be a to-and-fro with an unpredictable result.
UK Prime Minister Boris Johnson said he "unreservedly condemned" Mr Trump for inspiring the attack on the Capitol.
"Insofar as he encouraged people to storm the Capitol and insofar as the President consistently cast doubt on the outcome of a free and fair election, I think that was completely wrong."
German Chancellor Angela Merkel mentioned Mr Trump by name and blamed him: "Doubts about the election outcome were stirred and created the atmosphere that made the events of last night possible."
"A ground rule of democracy is that after elections there are winners and losers. Both have their role to play with decency and responsibility so that democracy itself remains the winner."
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