On Thursday, Christopher Sean Harper-Mercer, 26, killed eight students and their English professor in a classroom at Umpqua Community College in Roseburg, Ore.
The night before that shooting, someone posted on 4chan: "Some of you guys are alright [sic]. Don't go to school tomorrow if you are in the northwest [sic]."
That was posted with a cartoon image of a frog with human characteristics holding a gun. The same image - adding a ski mask - appeared with the threat to the Philly-area schools posted Friday.
Temple University, the University of Pennsylvania, Drexel University and La Salle University all sent safety alerts on Sunday notifying students that the Bureau of Alcohol, Tobacco & Firearms and the FBI were aware of an unspecific threat directed at "a university near Philadelphia," that could happen at 2 p.m. Eastern Time Monday.
The post about Philadelphia, posted on 4chan's "ROBOT9001" or "r9k" board, says: "The first of our kind has struck fear into the hearts of America."
"If you are in that area, you are encouraged to stay at home and watch the news as the chaos unfolds," the post about Philly reads.
The 4chan site, a message board started in 2003 by 15-year-old Christopher Poole, is a spinoff of the Japanese website 2chan. Users start a thread with an image and invite discussion about topics segregated into boards about topics including anime, gaming, music, and several varieties of hentai pornography. It's the breeding ground of "Anonymous," the hacker/ protester collective.
Posts on the site have invited controversy before. In 2006, a user posted a detailed plan to detonate bombs at seven NFL stadiums on game day. The poster later served six months in prison.
"R9K" is powered by a script that prevents repeated posts from going on the site, forcing every post to be original.
Law-enforcement agencies have not released information about who made either the Oregon threat or the Philly threat.
Jong Lee, 20, a junior at Temple, told the Daily News on Sunday that he searched Google for some terms used in the university's alert, which was emailed to students. He soon found a website that archives old 4chan posts, and sent a screenshot to the People Paper.
Lee says he's still going to class today, and won't let the threat affect his routine.
Sean Collins, 19, a math major at Penn, said he's planning to go about his day as normal, although the 4chan post was "a little more upsetting" than the message Penn sent to students about the threat.
"It could be someone trying to get attention," he noted. But Collins is glad the police will be patrolling in greater numbers.
"They're doing, as far as we know, all they can with the information they have," he said.
Rebecca Uhl, a marketing major at Temple, isn't changing her routine either. When 2 p.m. rolls around, she'll be studying for a class at 2:30 p.m., she told the People Paper.
"It wasn't a tough decision," she said. "My professor takes attendance and it's an important class."