Departments at two campuses received about a dozen e-mails Thursday threatening "violence against numerous persons." Officials said the college, which serves about 10,000 day students, decided to close down its campuses in Exton, Downingtown, Marple, Sharon Hill and Broomall in Delaware County.
Authorities said they were trying to track down the sender, whom they suspected might be a student, and focusing on the Exton campus. College officials said they would not reopen the campuses until they were assured by authorities it was safe to do so.
CBS Station KYW correspondent Walt Hunter said the words on the e-mails that were received by eight staff and administrators were "frightening and ominous."
"This was a disturbed young man, a disturbed individual," Sgt. Martin Malloy of the West Whiteland Police Department told KYW.
"The sender indicated that he was stressed out, and made communications that were rather disturbing of actions he may take in the near future."
Detectives hope search warrants will lead them to the computer that was the source of the threats — and to the person who sent them.
Officials said the closure was prompted in part by the massacre earlier this month at Virginia Tech, in which 33 people died in the deadliest shooting rampage in modern U.S. history.
Elsewhere, police with bomb-sniffing dogs searched every building at Penn State's Abington campus Sunday because of a bomb threat, but found nothing and said classes would be held as scheduled Monday.
The threat, discovered two days before the Virginia Tech shootings, was spray-painted on a bathroom wall and mentioned Monday's date, according to Chuck Marsh, the director of university relations for the suburban Philadelphia campus.
Police said they did not consider the threat credible, but in light of the Virginia shootings decided to take extra precautions. Classes were to be held as scheduled Monday, but with extra security provided by university police, Abington Township police and state troopers.