In the wake of the Las Vegas massacre, which saw gunman Stephen Paddock use an arsenal of 23 weapons—including numerous legally purchased semiautomatic assault rifles legally modified with bump stocks to make them fully automatic—to kill at least 58 people and injure 527 more, social media sites like Facebook and Google aided in the spreading of fake news.

The far-right blog Gateway Pundit, which has a reputation for misidentifying terrorists following mass shootings, published a post falsely identifying Geary Danley as the Vegas shooter, with its headline reading, “Las Vegas Shooter Reportedly a Democrat Who Liked Rachel Maddow, MoveOn.Org and Associated with Anti-Trump Army.” Danley was not the shooter, but rather the first husband of Marilou Danley, the girlfriend of Paddock’s and a “person of interest” in the case.

That didn’t stop the false Gateway Pundit story from rocketing to the top of Facebook’s Crisis Response page in the early hours Monday (the page also promoted a false Danley-smearing story from a sketchy site called Alt-Right News.) If that weren’t enough, the false Gateway Pundit piece was a top search result for Danley’s name on Google early Monday, where it was joined by a bogus 4Chan thread connecting Danley to the shooting. Many of the top search results for the Vegas shooting on YouTube—which, like Google, is owned by Alphabet Inc.—further promoted disgusting conspiracy-theory videos claiming the shooting was a hoax.

“Fake news online is a major problem—especially considering that two-thirds of adults in America say that they get some of their news from social media,” said The Daily Show host Trevor Noah on Wednesday night.

Noah dedicated a segment of his program to the corrosiveness of “online news going haywire,” pointing to the fake news spread by social-media sites in the wake of the Las Vegas tragedy.

“That’s right: Millions of people are now linking an innocent man’s face to a mass shooting, which is really messed up, when you think about it,” said Noah of Geary Danley. “This poor guy’s walking around trying to live his life with people probably walking up to him and saying, ‘Hey, are you the guy that shot everyone and then killed himself? Not cool, man. Not cool. Hey, can I get a selfie?”

It’s not just the Vegas massacre, either. Noah emphasized that the spread of genuinely “fake news” is a problem “all across social media,” pointing to how 10 million Americans saw Russia-linked ads on Facebook before and after the recent presidential election, with many of the ads targeting swing states Michigan and Wisconsin (which proved crucial to Trump’s election victory). Fake news on Twitter also “flooded swing states that helped Trump win,” reported Mother Jones. And, as The Daily Beast reported, a Kremlin-backed troll farm helped spread memes online weighing in on the recent NFL national anthem protests against police brutality.

“And now, regardless of your politics, the reason you should care about fake news online is because it’s not just about Russians meddling in U.S. elections,” said Noah, “it’s about Russians working to divide everyone.”