SAN FRANCISCO — On Twitter, customers known as on Wednesday for the corporate’s chief govt, Jack Dorsey, to take down President Trump’s account.

Civil rights teams weighed in, saying motion by social media corporations towards requires political violence was “long overdue.” And 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 is just not 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. “If you happen to work at these corporations, it’s on you too. Shut it down.”

As pro-Trump protesters stormed the Capitol building on Wednesday and halted the certification of Electoral Faculty votes, the position of social media corporations akin to Twitter, Fb and YouTube in spreading misinformation and being a megaphone for Mr. Trump got here underneath renewed criticism.

For years, Mr. Trump had constructed his affect with rapid-fire tweets and by reaching out to hundreds of thousands of individuals on Fb. Since dropping November’s election, he had used the platforms to problem the election outcomes and name them fraudulent.

Twitter, Fb and others had lengthy resisted cracking down on Mr. Trump’s posts and different poisonous content material. 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 posts and as an alternative took half steps, akin to 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 residence to roost for the social media corporations.

“We all know the social media corporations have been lackadaisical at greatest” at stopping extremism from rising on their platforms, mentioned Jonathan Greenblatt, director of the Anti-Defamation League. “Freedom of expression is just not the liberty to incite violence. That isn’t 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.

“It is a demonstration of the very real-world impression of echo chambers,” she mentioned. “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 not directly saved on-line. I hope that this eliminates the conception from individuals’s minds.”

Fb, Twitter and YouTube mentioned on Wednesday that they had been reviewing the scenario and wouldn’t tolerate requires violence on their websites. In a statement, Twitter mentioned it will take motion towards tweets that violated its insurance policies and was “exploring different escalated enforcement actions.”

YouTube mentioned it eliminated a number of reside streams that confirmed contributors storming the Capitol constructing carrying firearms. It additionally mentioned it will elevate authoritative information sources on its residence web page, search outcomes and in suggestions.

“The violent protests within the Capitol immediately are a shame,” added Andy Stone, a Fb spokesman. “We prohibit incitement and requires violence on our platform. We’re actively reviewing and eradicating any content material that breaks these guidelines.”

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

Twitter later added a label to Mr. Trump’s video, saying its claims of fraud had been disputed and will result in violence. Fb and YouTube eliminated the video fully.

Critics mentioned the statements by Fb, Twitter and YouTube had 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 known as Purple-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 outstanding progressive politicians.

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

Fb mentioned it eliminated Purple-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 had 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 imagine 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!,” mentioned one Parler account member known as @Trumpfans100, providing no proof for the claims.

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

What Fb, Twitter and YouTube could do subsequent is unclear. Over the previous yr, a few of the corporations have stepped up efforts to reasonable 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 yr 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.

At each Fb and Twitter, executives met on Wednesday to determine learn how to react, based on individuals with data of the businesses. Fb staff have combed the social community for public examples of protest group and have taken down quite a lot of hashtag phrases that had been used to coordinate the protests on Wednesday.

“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 these kind of harmful actions,” Derrick Johnson, president and chief govt of the N.A.A.C.P., mentioned in an interview. “That is an instance of the place each our democracy is being undermined and the place persons are not being saved secure. They need to droop the president’s account instantly.

Daisuke Wakabayashi contributed reporting.