UPDATE: It took almost six hours for Harvard University to reopen the four buildings evacuated after an emailed threat. That email mentioned explosives, though none were found.
Finals are underway at the Ivy League school and the alert was sent just as exams were about to begin.
A number of police agencies are interested in the source of the unfounded threat.
(CAMBRIDGE, Mass.) -- Harvard University has ordered several buildings on campus to be evacuated following unconfirmed reports of explosives.
"Alert: Unconfirmed reports of explosives at four sites on campus: Science Center, Thayer, Sever, and Emerson. Evacuate those buildings now," @Harvard tweeted Monday morning.
The university added, "There have been NO reports of explosions."
The school says both the Harvard University Police Department and Cambridge Police Department are on the scene and investigating. Federal and state officials have also joined the investigation.
Exams that were scheduled to take place in the affected locations have been canceled, the Harvard Crimson reports.
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