Hours after hundreds of President Donald Trump’s supporters stormed the US Capitol in a harrowing assault on American democracy, a shaken Congress on Thursday formally certified Democrat Joe Biden’s election victory.

Immediately after the certification, the White House released a statement from Trump in which he pledged an “orderly transition” on Jan. 20 when Biden will be sworn into office.

Congress had resumed its work certifying Biden’s Electoral College win late on Wednesday after the chaotic scenes on Capitol Hill, with debate stretching into the early hours of Thursday.

After debate the Senate and the House of Representatives rejected two objections to the tally and certified the final Electoral College vote with Biden receiving 306 votes and Trump 232 votes.

Vice President Mike Pence, in declaring the final vote totals behind Biden’s victory, said this “shall be deemed a sufficient declaration of the persons elected president and vice president of the United States.”

Vice President-elect Kamala Harris will take office alongside Biden on Jan. 20.

The outcome of the certification proceedings had never been in doubt, but had been interrupted by rioters – spurred on by Trump – who forced their way past metal security barricades, broke windows and scaled walls to fight their way into the Capitol.

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.

The assault on the Capitol was the culmination of months of divisive and escalating rhetoric around the Nov. 3 election, with the Republican president repeatedly making false claims that the vote was rigged and urging his supporters to help him overturn his loss.

Trump persisted in making the false claims he had won even as he said the transition would be orderly.

“Even though I totally disagree with the outcome of the election, and the facts bear me out, nevertheless there will be an orderly transition on January 20th,” he said in a statement posted on Twitter by White House spokesman Dan Scavino.

Wednesday’s chaos unfolded after Trump - who before the election refused to commit to a peaceful transfer of power if he lost - addressed thousands of supporters near the White House and told them to march on the Capitol to express their anger at the voting process.

He told his supporters to pressure their elected officials to reject the results, urging them “to fight.”

Some prominent Republicans in Congress strongly criticized Trump, putting the blame for the day’s violence squarely on his shoulders.

“There is no question that the President formed the mob, the President incited the mob, the President addressed the mob. He lit the flame,” House Republican Conference Chairwoman Liz Cheney said on Twitter.

Republican Senator Tom Cotton, a leading conservative from Arkansas, called on Trump to accept his election loss and “quit misleading the American people and repudiate mob violence.”