"The Harvard University Police Department (HUPD) this morning received an unconfirmed report that explosives may have been placed in four buildings on campus: the Science Center, Thayer, Sever and Emerson Halls," a message on the University's website read.

"HUPD and Cambridge Police are on the scene. Out of an abundance of caution, the buildings have been evacuated while the report is investigated. Harvard's focus is on the safety of our students, faculty and staff. We will update the media when we have more information," it said.