Following yesterday’s tragic school shooting at a community college in Oregon that left at least 10 people dead, federal authorities are investigating what appears to be a potential warning on September 30 about the shooting before it occurred. An anonymous user on a messageboard called /r9k/ on notorious website 4chan notified others, “Don’t go to school tomorrow if you are in the northwest.” The New York Times reports that dozens of FBI agents are assisting in the investigation.

Authorities are combing other social media to determine if there is a credible connection after police shot and killed the shooter. The Washington Post reported that shooter Chris Harper Mercer was active online, frequenting a variety of dating sites and MySpace.

In a strange coincidence, yesterday was also the 12th anniversary of the founding of 4chan.

Screenshot of the post in question.

Founded in 2003 as an anonymous message board, 4chan has grown in reputation as a kind of Wild West for internet trolls, puerile humor, and digital flotsam of all sorts. Internet entrepreneur Christopher Poole modeled the site after a similar image-based Japanese site called Futaba Channel (2ch.net). It was initially used as a way to share foreign language images of anime and translate them into English; now it logs 22 million U.S. users per month. This year, Poole sold the sprawling group of forums to Hiroyuki Nishimura, who started 2channel. Poole at the time was 4chan’s only official employee.

Users who would otherwise have to register their identities to other message boards flock to 4chan to discuss a range of taboo topics: child porn, white supremacy, hacking, crime. After posting the “Don’t go to school” message, other anonymous users urged the original poster on with their violent intentions. One responded: “I suggest you enter a classroom and tell people that you will take them as hostages. Make everyone get in one corner and then open fire.” Another wrote: “You might want to target a girls school which is safer because there are no beta males throwing themselves for their rescue.”

A MySpace photo of shooter Christopher Harper Mercer.

Though the identity of the anonymous poster has not been identified as Mercer, and outlets like the Times cautioning the link “may not be credible in any way,” authorities are still searching to create a complete picture.

Photos via https://archive.moe/r9k/thread/22785073/#22785073, Myspace, Getty Images