Princeton University reopened its campus at 6:25 p.m. Tuesday after a bomb threat forced an evacuation of the New Jersey campus for about eight hours, university officials said.
No explosive devices were found after law enforcement authorities and bomb-sniffing dogs inspected the university's buildings and grounds, the university said in a statement.
The bomb threat was phoned in and mentioned "multiple unspecified campus buildings," so authorities conducted a meticulous search of the entire campus.
Faculty and visitors were asked at about 10:30 a.m. to evacuate the campus immediately. An hour later, cars were streaming out of campus lots.
No classes were in session, though university spokesman Dan Day says there are some summer programs on campus.
A spokesman with the FBI's New Jersey office told NBC 4 New York the FBI is assisting Princeton University police in the investigation.
"The University takes all threats to the safety and well being of our community members and visitors seriously and is fully cooperating with the ongoing investigation," the university said in a statement.