In the immediate aftermath of the Las Vegas shooting, people turned to Facebook and Google, looking for news about what happened and, in some cases, updates about their friends and loved ones in the area.
What they were presented with, in some cases, was misinformation.
Perhaps the most egregious strain of misinformation took hold after far-right trolls gathered on 4chan, a forum in which individuals are permitted to post almost anything anonymously, and, through some amateur online sleuthing, misidentified the shooter. The false claim spread quickly on the Internet.
The Gateway Pundit, a far-right website, published a story declaring that the person 4chan had named was the culprit. It described him as someone thought to be "a Democrat who liked Rachel Maddow, MoveOn.org, and associated with the anti-Trump army." (The Gateway Pundit later deleted the story. Its White House correspondent, Lucian Wintrich, told CNN the website removed the story soon after it was posted, and that it regretted the error.)
Other websites published similar claims which were then amplified by Google. Anyone who searched Google for the name of the person wrongly identified would see among the top results links to the websites that carried the false claim.
In its "Top Stories" section, a space that features breaking stories on search queries and is located at the top of the page, Google's first recommended link was to one of the 4chan boards in which the wrong person was blamed for the massacre.
In a statement, a Google spokesperson conceded that the search engine giant's algorithm was "briefly surfacing an inaccurate 4chan website" for what it said was a "small number of queries."
"Within hours, the 4chan story was algorithmically replaced by relevant results," the Google spokesperson said. "This should not have appeared for any queries, and we'll continue to make algorithmic improvements to prevent this from happening in the future."
But the less-than-reliable news circulating in the aftermath of the Las Vegas attack didn't stop with Google.
Facebook promoted several dubious websites on its Crisis Response page, the social media platform's go-to destination that allows friends and family to see if loved ones have checked in and are safe.
Among the outlets promoted by Facebook were The Gateway Pundit; a blog called Alt Right News; and several websites of questionable credibility.
"Our Global Security Operations Center spotted these posts this morning and we have removed them," a Facebook spokesperson told CNN. "However, their removal was delayed, allowing them to be screen captured and circulated online. We are working to fix the issue that allowed this to happen in the first place and deeply regret the confusion this caused."
The boosting of misinformation comes at a bad time for both Google and Facebook. Both tech companies are facing questions about possible roles they may have inadvertently played in Russia's campaign to influence the 2016 election.
Facebook on Monday turned over to Congress 3,000 ads linked to a Russian troll farm. Google is conducting an internal investigation into possible Russian meddling on its platform, a Google source with knowledge of the matter previously told CNN.