8CHAN: Three mass shootings this year began with a hateful screed on 8chan, whose founder calls it a terrorist refuge in plain sight.

The El Paso massacre began like the fatal attacks earlier this year at mosques in New Zealand and a San Diego-area synagogue: with a racist manifesto and announcement on the anonymous message board 8chan, one of the web’s most venomous refuges for extremist hate.

And like after the mass shootings in Christchurch and the Chabad of Poway synagogue, the El Paso attack was celebrated on 8chan as well: One of the most active threads there early Sunday urged people to create memes and original content, or OC, that could make it easier to distribute and “celebrate the (gunman’s) heroic action.”

The message board’s ties to mass violence have fueled worries over how to combat a web-fueled wave of racist bloodshed. The El Paso shooting also prompted the site’s founder early Sunday to urge its current owners to “do the world a favor and shut it off.”

“Once again a terrorist used 8chan to spread his message as he knew people would save it and spread it,” Fredrick Brennan, who founded 8chan in 2013 but stopped working with the site’s owners in December, told The Washington Post. “The board is a receptive audience for domestic terrorists.”

Twenty people were killed at an El Paso shopping center following the attack by the suspected gunman, who posted a jumbled and racist screed to 8chan minutes before the shooting that ranted against a “Hispanic invasion.” The shooter wrote that he was inspired by the Christchurch massacre, which also began with an 8chan post, and he urged viewers to “do your part and spread this brothers!”

The El Paso shooting, some terrorism experts said, could ratchet up the pressure on federal law enforcement and governmental authorities seeking to combat a site that calls itself “the darkest reaches of the internet.”

The site has survived, extremism experts said, in part due to a reluctance from some law-enforcement and intelligence officials to categorize white-supremacist and far-right movements as terror threats. The site has for years been shielded by U.S. laws that limit websites’ legal liability for what their users post, and has been further protected by an internet infrastructure that makes it difficult to take sites down.

Some online researchers also fear a shutdown of 8chan would only spur hate groups to organize elsewhere. The site’s leaders have appeared emboldened in the face of criticism, adding a message in recent months at the top of its homepage: “Embrace infamy.”

The site is registered as a property of the Nevadabased company N.T. Technology and owned by Jim Watkins, an American web entrepreneur living in the Philippines. Asked for comment, Watkins replied with a single sentence: “I hope you are well.”

Watkins has declined interview requests after every mass shooting. Following the Christchurch massacre, he released a video defending the site as a refuge for free speech online and referring to the shooter as a criminal alien.

Watkins’ son, Ron, who oversees the site, did not respond to requests for comment. He has mocked the idea that 8chan could do more to stop mass violence, tweeting in April: “Deletion within minutes is not enough, apparently.”

Joan Donovan, the director of the Technology and Social Change Research Project at Harvard University’s Shorenstein Center, said posting to 8chan before a mass shooting has become a “tactical” way for attackers to gain attention and amplify their message.