The US Congress certified Joe Biden’s election as the 46th president of the United States early on Thursday morning after a delay caused by the storming of the Capitol by rioters supporting outgoing President Donald Trump. Votes in the Senate and House of Representative dismissed challenges raised by Republicans to the results of the November 3 election in which the Democratic candidate and his running mate Kamala Harris defeated Mr Trump and Vice President Mike Pence with 306-232 electoral college votes. The House rejected a challenge to Mr Biden's win in the state of Pennsylvania by a vote of 282 to 138 after a debate that ended after 3am. It earlier rejected a challenge to the result in Arizona by 303 to 121. The Senate rejected the Pennsylvania challenge by 92 votes to 7 and the Arizona challenge by 93 to 6. The late-night votes followed unprecedented chaos on Capitol Hill that forced the session to be delayed. Pro-Trump rioters stormed the Capitol building, where they clashed with police and destroyed federal property. One woman was killed during the clashes. Congressional leaders were taken to secure locations, a curfew was imposed in DC and the Capitol was on lockdown for five hours until the National Guard was deployed and secured the building. The events were unparalleled and have posed a challenge to US democracy, as well as exposing security vulnerabilities around the Capitol. Mr Biden called the riot an “insurrection” and assault on US democracy. "At this hour, our democracy is under unprecedented assault…I call on this mob to pull back and allow the work of democracy to go forward.” Unlike Mr Trump, who continued to spread misleading information about the US election, Mr Pence conceded the loss and proclaimed Mr Biden as president. Mr Pence also offered a strong defence of US democracy. "To those who wreaked havoc in our Capitol today, you did not win…Violence never wins. Freedom wins. And this is still the people's house,” Mr Pence said. Senate Majority Leader Mitch McConnell called the riots a "failed insurrection" while other Republicans such as Kelly Loeffler, a senator from Georgia, dropped their objections to Mr Biden’s win after the violence. Pressure and criticism piled up for Mr Trump who continued to insist that the election was “fraudulent”. Twitter removed two of the president's tweets, locked his account for 12 hours, and said it might suspend him from the platform permanently if he continued to violate its policies. Facebook locked Mr Trump’s account for 24 hours. At least three senior White House officials resigned on Wednesday after the violence. Stephanie Grisham, the chief of staff to first lady Melania Trump, Sarah Matthews, the deputy press secretary, and Rickie Niceta, the White House Social Secretary, stepped down from their roles. More high-level resignations could follow, including national security adviser Robert O’Brien, NBC reported. The 25th amendment was also brought up in debate on Wednesday, CBS reported. The amendment allows for a president to be removed from office on the basis of being unfit, after which the vice president would assume power. But this would require a vote by the US Cabinet and support from Mr Pence as well as Congress. Reuters reported that Jay Timmons, the chief executive of the National Association of Manufacturers, had urged senior US officials to consider removing Mr Trump. The outgoing US president has only two weeks left in office. Mr Biden and Ms Harris will be sworn in on January 20.