UPDATE, 3:25 p.m. ET: Harvard has given the all clear.
"All four sites now open," the school said.
UPDATE, 1:00 p.m. ET: Fox News reports two of the four buildings have been cleared after an unconfirmed report threatened campus buildings.
UPDATE, 12:30 p.m. ET: Authorities continue to search the Harvard University campus after an unconfirmed report of explosives threatening four campus buildings.
The Harvard University Police Department responded Monday to an "unconfirmed report that explosives may have been placed in four buildings on campus," the school said.
In an emergency alert posted on Harvard's website, the Ivy League school said the Science Center, Thayer, Server and Emerson buildings had been evacuated as police investigate the threat.
"Out of an abundance of caution, the buildings have been evacuated while the report is investigated," Harvard said. "Harvard's focus is on the safety of our students, faculty and staff."
The Department of Homeland Security, FBI and bomb squad officers are also investigating the threat, Fox News and The Boston Globe reported.
According to student newspaper The Harvard Crimson, Dean of Undergraduate Education Jay Harris canceled all final exams for the morning.
Harvard is located in Cambridge, Mass., near the site of April's Boston Marathon bombings that killed three people and injured hundreds with explosives made from pressure cookers.
This is a breaking news story. Updates will be added.
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