SAN FRANCISCO — Twitter and Fb on Wednesday locked the accounts of President Trump, which prevents him from posting messages to his greater than 88 million followers on Twitter and 35 million followers on Fb, after he printed a string of inaccurate and inflammatory messages on a day of violence in the nation’s capital.

The strikes have been an unprecedented rebuke of Mr. Trump by the social media firms, which have lengthy been megaphones for the president.

Twitter stated Mr. Trump’s account would stay locked for 12 hours and the ban might be prolonged if a number of of his tweets that rejected the election outcomes and appeared to incite violence weren’t deleted. Mr. Trump’s account will probably be completely suspended if he continues violating Twitter’s insurance policies towards violent threats and election misinformation, the corporate added.

Twitter stated the dangers of conserving Mr. Trump’s commentary reside on its web site had develop into too excessive. “Our public curiosity coverage — which has guided our enforcement motion on this space for years — ends the place we consider the chance of hurt is increased,” a spokesman stated.

Fb later adopted by barring Mr. Trump from publishing on the social community for twenty-four hours after discovering that he had violated the corporate’s guidelines with two posts, a Fb spokesman stated.

The actions adopted a torrent of criticism aimed toward social media firms for his or her position in spreading misinformation and being a bullhorn for Mr. Trump after a pro-Trump mob stormed the Capitol building on Wednesday and halted the certification of Electoral School votes. For years, Mr. Trump had constructed his affect with posts on Twitter and Fb. Since dropping November’s election, he had used the platforms to problem the election outcomes and name them fraudulent.

On Twitter on Wednesday, customers referred to as for the corporate’s chief govt, Jack Dorsey, to take down President Trump’s account. Civil rights teams stated motion by social media firms towards requires political violence was “long overdue.” Even enterprise capitalists who had reaped riches from investing in social media urged Twitter and Fb to do extra.

“For 4 years you’ve rationalized this terror. Inciting violent treason shouldn’t be a free speech train,” Chris Sacca, a tech investor who had invested in Twitter, wrote to Mr. Dorsey and Fb’s chief govt, Mark Zuckerberg. “Should you work at these firms, it’s on you too. Shut it down.”

Twitter, Fb and others had beforehand resisted cracking down on Mr. Trump’s posts and different poisonous content material, saying that the posts have been within the public’s curiosity. Whereas the platforms had began taking extra steps towards political misinformation within the months earlier than the election, they declined to take away Mr. Trump’s messages and as a substitute took half measures, reminiscent of labeling his posts.

So when violence broke out in Washington on Wednesday, it was, within the minds of longtime critics, the day the chickens got here dwelling to roost for the social media firms. After the onslaught of criticism started, Twitter and Fb began eradicating a number of of Mr. Trump’s posts from their websites, together with one the place the president falsely stated that “a sacred landslide election victory” had been “unceremoniously & viciously stripped away.”

“We all know the social media firms have been lackadaisical at finest” at stopping extremism from rising on their platforms, stated Jonathan Greenblatt, director of the Anti-Defamation League. “Freedom of expression shouldn’t be the liberty to incite violence. That’s not protected speech.”

Renee DiResta, a researcher on the Stanford Web Observatory who research on-line actions, added that the violence was the results of individuals working in closed social media networks the place they believed the claims of voter fraud and of the election being stolen from Mr. Trump.

“This can be a demonstration of the very real-world affect of echo chambers,” she stated. “This has been a hanging repudiation of the concept that there may be a web based and an offline world, and that what is claimed on-line is in a roundabout way saved on-line. I hope that this eliminates the conception from individuals’s minds.”

YouTube additionally stated on Wednesday that it might not tolerate requires violence on their websites. The video web site stated it eliminated a number of reside streams that confirmed members storming the Capitol constructing carrying firearms. It additionally stated it might elevate authoritative information sources on its dwelling web page, search outcomes and in suggestions.

Mr. Zuckerberg stated in an inside memo to workers that he was “saddened by this mob violence,” in keeping with a duplicate reviewed by The New York Occasions. He stated Fb had stepped up the moderation of Mr. Trump’s feedback as a result of the state of affairs was “an emergency.”

“The peaceable transition of energy is crucial to the functioning of our democracy, and we’d like our political leaders to steer by instance and put the nation first,” Mr. Zuckerberg wrote.

Mr. Trump additionally instructed his supporters to go dwelling in a video that he posted on a number of social media websites on Wednesday afternoon. “It’s a must to go dwelling now. We’ve got to have peace. We’ve got to have legislation and order,” he stated, whereas repeating false claims that the election had been stolen from him.

Twitter later eliminated three tweets, together with the video and the tweet by Mr. Trump inaccurately claiming a “sacred landslide election victory” earlier than locking his account. YouTube additionally deleted the video, as did Fb, which additionally took down the deceptive submit by Mr. Trump on the “election victory.”

Critics stated the strikes by Fb, Twitter and YouTube have been too little, too late, after requires violence and plans for protests had already unfold on the platforms.

On Fb, protesters had overtly mentioned what they aimed to do in Washington on a Fb web page referred to as Crimson-State Secession for weeks. The web page had requested its roughly 8,000 followers to share addresses of perceived “enemies” within the nation’s capital, together with the house addresses of federal judges, members of Congress and distinguished progressive politicians.

Feedback left on the web page typically featured photographs of gun and ammunition, together with emojis suggesting that members of the group have been planning for violence. One submit on Tuesday stated individuals must be “ready to make use of power to defend civilization.” A number of feedback beneath the submit confirmed photographs of assault rifles, ammunition and different weapons. Within the feedback, individuals referred to “occupying” the capital, and taking motion to power Congress to overturn the outcomes of the elections.

Fb stated it eliminated Crimson-State Secession on Wednesday morning. Earlier than it was taken down, the web page directed followers to other social media sites like Gab and Parler which have gained reputation in right-wing circles because the election.

These different social media websites have been rife with Trump supporters organizing and speaking on Wednesday. On Parler, one trending hashtag was #stormthecapitol. Many Trump supporters on the websites additionally appeared to consider a false rumor that Antifa, a left-wing motion, was answerable for committing violence on the protests.

“WAKE UP AMERICA, IT’S ANTIFA and BLM operatives who’re committing the violence, NOT TRUMP SUPPORTERS!,” stated one Parler account member referred to as @Trumpfans100, providing no proof for the claims.

Officers at Parler didn’t instantly reply to a request for remark.

Over the previous 12 months, Fb and Twitter had stepped up efforts to average Mr. Trump’s account, although they’ve stopped wanting taking down his posts. Twitter started including labels to Mr. Trump’s false and deceptive tweets final 12 months and has prevented customers from sharing the posts to restrict their unfold. Fb has additionally connected labels to a few of Mr. Trump’s posts, redirecting customers to dependable and correct information.

When Mr. Trump leaves workplace, the businesses might have a freer hand. On Twitter, Mr. Trump had largely loved exceptions to its guidelines as a result of the corporate has stated it considers posts from world leaders to be within the public curiosity. However Twitter has stated that after Mr. Trump is not president, he will probably be handled like an everyday consumer.

“This stage of revolt shouldn’t exist, whether or not it’s on the Twitter platform from the president, or whether or not it’s on Fb, which permits individuals to recruit and perform some of these harmful actions,” Derrick Johnson, president and chief govt of the N.A.A.C.P., stated in an interview.

Daisuke Wakabayashi contributed reporting.