Facebook (FB), Twitter (TWTR), and other social media sites should be held accountable for helping to stoke the divisiveness that led to Wednesday’s attack on the Capitol, according to a former Obama adviser who has also worked for Facebook.

Dozens of Trump supporters stormed the Capitol seeking to overturn the 2020 election results after the president used a nearby rally and his Twitter account to spread lies about the election and incite violence among his followers.

“These are the things and events that happen when a sacred landslide election victory is so unceremoniously & viciously stripped away from great patriots who have been badly & unfairly treated for so long. Go home with love & in peace. Remember this day forever!” Trump wrote in a now-deleted tweet.

Four people died during the attack, including a U.S. Air Force veteran who embraced conspiracy theories on her own social media accounts. A fifth person, a Capitol Hill police officer, died on Thursday night from injuries sustained during the riot.

“I think they should be held responsible. I think they are, in large part culpable for all the harm, all the hate, all the death that we saw yesterday,” Dipayan Ghosh, co-director of the Harvard Kennedy School Digital Platforms & Democracy Project, told Yahoo Finance Live on Thursday.

A former economic adviser under President Barack Obama and the former Facebook privacy and public policy adviser, Ghosh, as well as a growing number of scholars, is calling for social networks to face consequences for enabling the spread of the lies, hate speech, and conspiracy theories that led to the Capitol attack.

According to Ghosh, the machine learning algorithms that serve up the content users see on social media platforms to bring in advertising dollars have gone out of control, and need to be reined in.

“To get it back under control, we need to put not the commercial interests of companies like Facebook as the objective for these algorithms, but rather the public interest, what we want to see, what is socially acceptable political speech and content on thinks kinds of platforms,” he said.

In the midst of the attack on the Capitol, Trump posted a video as well as statements on Facebook, Twitter, and YouTube (GOOG, GOOGL) further fanning the flames of violence by falsely asserting the 2020 election had been stolen from him, prompting the sites to remove his posts or block him entirely.

Facebook, on Thursday, took the extraordinary step of suspending Trump’s accounts on Facebook and Instagram indefinitely, while Twitter initially suspended his account for at least 12 hours. Twitter permanently banned Trump on Friday.

The move by Facebook marks a complete turnaround for CEO Mark Zuckerberg, who for years, said he would allow politicians and political advertisements to continue to lie on his platforms, because he didn’t want the company serving as the arbiter of truth. Facebook has said it would only place warnings on posts or remove them if they could result in real-world harm.

MIT management professor Sinan Aral, meanwhile, told Yahoo Finance Live on Wednesday that he’s concerned about what social media platforms, which the Trump supporters used to help organize their movements, could bring about in the coming days and weeks.

“What I’m really concerned about ... is what’s going to happen next, what’s going to happen tonight. What’s going to happen in the next two weeks before the Inauguration, and what is the information role in what happens tonight and in the next two weeks?” said Aral, author of “The Hype Machine: How social media disrupts our elections, our economy, and our health — and how we must adapt.”

“What’s Facebook’s role? ... What’s Twitter’s role?” he added. “How can we subvert the information, motivation, and mobilization of this kind of violence?”

According to Ghosh, legislation could be the answer, including changes to Section 230 of the Communications Decency Act, which gives social media sites broad protection from legal liability for content posted on their sites.

“I would expect that Democrats will team up with the Biden administration, maybe even moderate Republicans, will team up with the Biden administration, and try to do something about Section 230,” he said, adding that lawmakers could also investigate social media companies’ data collection practices.

Such an outcome could be more likely to come to fruition as Democrats will control both Houses of Congress and the White House when Biden takes office on Jan. 20.

Editor’s note: This article was updated on Jan. 10 to reflect the death of a Capitol Hill police officer and the news that Twitter had banned Trump permanently.

Got a tip? Email Daniel Howley at [email protected] over via encrypted mail at [email protected], and follow him on Twitter at @DanielHowley.

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