Matt Jarbo was playing video games Tuesday afternoon when he got a Twitter notification.
Someone had spotted tweets circulating with pictures of Jarbo falsely accusing him of being the active shooter inside YouTube headquarters in San Bruno, Calif.
As the host of a news commentary channel on YouTube with more than 160,000 subscribers, Jarbo is no stranger to internet trolls. But making light of a tragedy inside a company that helped him build his career made him angry.
"A woman is dead and people are injured," said Jarbo, who's based in Washington state. "I get there's gallows humor on the internet, but I take what happened very personally."
In what's become a troubling tradition after a mass shooting, conspiracy theories and hoaxes bounced across social media soon after gun violence erupted inside YouTube's sprawling campus.
The behavior follows a pattern, most recently displayed after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Fla., last month. Innocent people were accused on Twitter of being the gunman. Students were accused of being crisis actors. And conspiracy theorists deemed the incident itself a hoax, or false flag, something that's further marred the aftermath of every major shooting, including at Sandy Hook Elementary.
On Tuesday, Twitter was flush with false accusations, much like those directed at Jarbo. Pictures of the purported shooter included women wearing head scarves, one of the earliest details spreading about what the assailant looked like.
Brittany Venti, a YouTube video creator, reposted several tweets that accused her of being the shooter.
"LOL," she wrote in response to one tweet that appeared to show a picture of her.
Other tweets blamed the attack on people who have been repeatedly subjected to false accusations after a mass shooting, such as comedian Sam Hyde.
A YouTube employee whose tweets about the attack had attracted a wide audience was also the victim of the misinformation campaign. Vadim Lavrusik, a manager with over 40,000 Twitter followers, tweeted about being on lockdown with his co-workers and later that he had safely evacuated the campus shortly after 1 p.m.
Then his account was hacked. The hacker wrote, among other things, "PLEASE HELP ME FIND MY FRIEND I LOST HIM IN THE SHOOTING," according to the Verge. The tweet reportedly linked to a photo of another popular YouTube video creator.
Twitter's chief executive, Jack Dorsey, tweeted that he would look into the hack.
In a tweet Tuesday afternoon, Twitter said it was attempting to stop the spread of misinformation. The company said it would delete any tweets that placed people in imminent danger.
"We are also aware of attempts by some people to deceive others with misinformation around this tragedy. We are tracking this and are taking action on anything that violates our rules," the company said.