Authorities are reporting that explosives have been reported to have been placed in four separate locations on the Harvard University campus.

12/16/2013 11:51am Harvard says that state and federal authorities are joining the probe to determine whether there are indeed explosives on campus.  Until they determine the next course of action activities - including exams - remain suspended.

Update: 12/16/2013 10:50am Authorities say they have found no explosives.  Access to Harvard Yard is limited to those with Harvard ID cards.

According to Harvard's latest Twitter feed Dean Jasmine Waddell is sitting with students in Annenberg Hall while the buildings remain evacuated:

Buildings have been evacuated and law enforcement officials are conducting a sweep of the campus.

According to Harvard's Twitter page the Cambridge Police Department and Harvard University Police are investigating.  The Science Center, Thayer, Sever, and Emerson Buildings have been evacuated.