Princeton University evacuated its campus Tuesday morning after receiving a phoned-in bomb threat to multiple buildings at the New Jersey campus.

According to the University's Twitter page, "Regular classes are over and Commencement was last Tuesday. Most students left campus days or weeks ago."

The Associated Press reports that no Princeton classes are in session, though some summer programs are. Princeton University is an Ivy League school, and one of the top universities in the United States.

Employees were asked to leave campus at around 10:30 a.m. Tuesday, according to CBS News. It was not clear which buildings or how many were included in the threat.

Princeton tweeted: "Bomb threat on campus. Pls evacuate campus and offices and go home. Updates to follow. Check email. NOT A TEST."

Their Twitter page also informed students with cars to leave campus and drive home immediately. Those without cars would be directed by police to evacuation sites.

Princeton's website posted the following warning: "There has been a bomb threat to multiple unspecified campus buildings. Please evacuate the campus and all University offices immediately and go home unless otherwise directed by your supervisor. Public Safety officers and Princeton Police will direct drivers leaving the campus and those without cars will be directed to evacuation sites. You will receive an update later today. Do not return to campus for any reason until advised otherwise."