Twitter said late Monday it purged more than 70,000 accounts affiliated with conspiracy theory QAnon following the deadly riot at the U.S. Capitol last week.

Twitter said in a blog post that it removed the accounts “to protect the conversation on our service from attempts to incite violence, organize attacks, and share deliberately misleading information about the election outcome.” The company said it began suspending the accounts on Friday afternoon, citing an increased risk of harm between online speech and real-world events.

Twitter’s purge Monday marked its latest effort to combat the rise of QAnon, a conspiracy theory that loosely revolves around the idea that an anonymous government official, known as Q, wages war against the so-called deep state that has sought to undermine President Trump. Trump himself in the past has amplified accounts tied to QAnon, helping to further its rise.

The crackdown came on a day when Amazon, Twitter and other tech companies confronted fresh blowback for a slew of other efforts to try to tackle harmful content online — including decisions to ban Trump and a wide array of websites that had glorified the violent mob that stormed the Capitol last week.

Twitter’s decision to remove Trump’s account, citing the potential that his corrosive rhetoric might incite additional violence, precipitated a sharp drop in the company’s shares, which fell by more than 6 percent Monday. Twitter also braced for a potential protest outside its San Francisco headquarters, a demonstration that the president’s supporters have sought to organize on pro-Trump forums in recent days. And leaders at both Facebook and Twitter advised employees to lower their social media profiles because some workers had received security and death threats.

Amazon, meanwhile, faced a new lawsuit from Parler, an alternative social network that had become a haven for Trump’s backers. Amazon Web Services, which provides cloud computing services, suspended its relationship with Parler starting Monday in a move that removed it from the Web — prompting Parler to allege that Amazon had acted unlawfully. Amazon shares also dipped slightly by afternoon.

(Amazon chief executive and founder Jeff Bezos owns The Washington Post.)

The flurry of activity reflected the still-intensifying clash between Washington and Silicon Valley in the days since Trump’s incendiary comments about the 2020 election helped spark the riot that forced the U.S. Capitol into lockdown and left five people dead.

Late Friday, Twitter banned Trump, citing two tweets, including one that said he is not planning to attend President-elect Joe Biden’s inauguration. Facebook earlier in the week also said it was suspending Trump indefinitely, and Sheryl Sandberg, the company’s chief operating officer, said in an interview with Reuters on Monday that there are “no plans to lift” the ban.

Twitter continued its efforts over the weekend, purging tens of thousands of accounts affiliated with the QAnon conspiracy theory, which had a large following among the rioters at the Capitol.

Those actions led to numerous high-profile conservative figures to report large drops in follower counts over the weekend — or to face suspension outright. The company would not comment on specific fluctuations in follower counts.

Former national security adviser Michael Flynn and former Trump attorney Sidney Powell were among those suspended, while House Minority Leader Kevin McCarthy (R-Calif.), Secretary of State Mike Pompeo and many other GOP politicians lost large numbers of followers.

“I don’t even understand what QAnon is,” said Powell in a statement. “I don’t follow it. Twitter is simply cracking down on conservatives, abusing its platform, breaching contracts, tortious interfering with businesses, and engaging in fascist suppression of truth and speech.”

Flynn didn’t immediately respond to a request for comment.

On Monday, Facebook announced a series of additional policy moves, including a new crackdown against posts that reference “stop the steal” — a rallying cry for Trump and others that have sought to delegitimize the outcome of the 2020 race. Ahead of Biden’s swearing-in ceremony, Facebook said it also would maintain its pause on political ads and aim to monitor its service more aggressively for harmful content, as it seeks to “stop misinformation and content that could incite further violence during the next few weeks,” executives said in a blog post.

Other tech giants have joined Twitter and Facebook in taking action against the president and his allies in recent days amid mounting political tensions in the United States — and growing fears about deadly violence still to come. That includes Parler, which Apple and Google removed from their app stores in a move that further constrained the right-leaning service’s reach. Joining Amazon, the tech giants each say Parler has not properly policed its platform for violent threats, an accusation Parler denies.

Trump responded to the Twitter ban with a statement late Friday promising to seek an alternate social network — or build one of his own — in an attempt to get around the vast digital blockade. Trump is expected to spend the final days of his presidency attacking Silicon Valley over allegations of censorship, according to a person familiar with the matter who spoke on the condition of anonymity to describe internal White House planning.

“We will not be SILENCED!” Trump said in the statement, which he previously had tried to tweet from the president’s @POTUS account before Twitter blocked it.

Twitter and its fellow tech giants deny the charges of censorship. The White House did not immediately respond to requests for comment.

Trump’s supporters, meanwhile, took to a forum sympathetic to the president, called TheDonald.win, to express their own displeasure. Some users even called for the execution of House Speaker Nancy Pelosi (D-Calif.) and other political figures, according to posts reviewed and compiled by the SITE Intelligence Group, which tracks online extremism. Others encouraged a protest at Twitter’s headquarters, though no such crowd had formed at the company’s offices by midday Monday.

“Maybe the hq should be burned down when everyone goes,” wrote one user on a widely trafficked thread.

A wide array of pro-Trump online communities, including TheDonald, had teemed with similar talk ahead of the riot at the Capitol last week — and since then they have glorified the violence that took place in Washington. The National Guard is set to deploy up to 15,000 troops during the inauguration in response to the heightened threats.

As users online lashed out, Parler filed a lawsuit against Amazon that alleges the company acted anti-competitively, and hypocritically, in choosing to suspend it. Twitter also hosted violent threats, according to lawyers from Parler, who asked a judge to grant a temporary restraining order to prevent Amazon “from shutting down Parler’s account.”

“Doing so is the equivalent of pulling the plug on a hospital patient on life support,” the lawsuit contends. “It will kill Parler’s business — at the very time it is set to skyrocket.”

Meanwhile, at Twitter, a companywide email was sent late last week advising employees to take care of their mental health, reminding them of ways to keep a low profile on social media about their employment status, according to a person familiar with the messages who spoke on the condition of anonymity due to concern about safety. Executives said it was important to support employees who had faced threats, according to the person.

Facebook executives sent out a companywide message Monday also noting that employees had faced threats and that people should minimize identifying information on social media, according to the document obtained by The Post.

Craig Timberg contributed to this report.

correction

Michael Flynn is former national security adviser. A previous version of this article referred to him as security adviser.