WASHINGTON, Jan. 6 (CNA) - Twitter and Facebook on Wednesday (Jan 6) temporarily locked the accounts of President Donald Trump, as tech giants scrambled to crack down on his baseless claims about the US presidential elections amid riots in the capital.

Twitter hid and required the removal of three of Trump's tweets "as a result of the unprecedented and ongoing violent situation in Washington, DC", after pro-Trump protesters stormed the US Capitol in an attempt to force Congress to block the appointment of President-elect Joe Biden.

One woman was shot and killed inside the Capitol building in the chaos.

Facebook later tweeted it would block Trump's page from posting for 24 hours due to two policy violations.

Twitter locked Trump's account for 12 hours and said that if the tweets are not removed, the account would remain locked, meaning the president would be unable to tweet from @realDonaldTrump.

Facebook and YouTube, owned by Alphabet's Google, also removed a video in which Trump continued to allege the presidential election was fraudulent even as he urged protesters to go home.

The video was removed from Instagram and the president's account there would also be locked for 24 hours, Adam Mosseri, chief of Facebook-owned Instagram, said in a tweet.

YouTube did not take any further immediate action against his account.

Tech companies have been under pressure to police misinformation on their platforms around the US election, including through calls by users on Wednesday for major platforms to suspend Trump's accounts.

The president and his allies have continuously spread unsubstantiated claims of election fraud that have proliferated online. Trump on Wednesday blamed Vice President Mike Pence for lacking "courage" to pursue those claims in a tweet that Twitter later took down.

A White House spokesman did not immediately respond to a request for comment.