Four times, they’ve all been a hoax, or what is generally known as swatting.

Campus leaders in Pennsylvania, Tennessee and South Carolina express gratitude the calls were false, and they’re trying to figure out next steps. At least one of two at Villanova University in Philadelphia was a call that came from off campus.

FBI detectives are involved, according to published reports from near the University of Tennessee at Chattanooga.

Chancellor Lori Bruce, in a letter to the community, says Thursday’s “original 911 call did not originate from campus. This incident was a criminal act, intended to be disruptive and cause chaos, but at no point was there a real threat to campus.”

Villanova President Rev. Peter Donohue called what transpired after a call to his campus about 4:30 p.m. on Thursday “panic and terror.” Sunday morning about 11 a.m., the campus got a second call that also turned out to be false.

AThe second call came from a student residence hall, Austin, according to reports. The Delaware County district attorney hasn’t said what happened on the first call four days earlier.

In Columbia, S.C., on Sunday evening, campus activities stopped for 95 minutes because of a reported gunman near a library. Authorities haven’t said how that call originated.

All four campuses are large. The undergraduate enrollments are about 7,000 at Villanova, 10,000 at UT-Chattanooga, and more than 46,000 at South Carolina.

The hoaxes are being characterized as swatting. That’s the act of a giving false information to emergency responders in order to have a large number of armed lawmen at a particular address.

A fifth incident happened on Tuesday of last week at Doane University, a school of about 2,000 in Crete, Neb. An armed suspect was reported but never found.

In an April 29 public service announcement, the FBI said, “The FBI takes swatting threats seriously and coordinates with federal, state, local, tribal and territorial law enforcement partners to respond to and investigate these incidents.”