UPDATE: At 1:15 p.m., Harvard reported the campus re-opened. See the comments for Cambridge PD statement.
Focus centers on the Science Center and Prescott Street, where a caller claimed to have put a bomb, Matthew George reports.
At 10:11, Nina Khosrowsalafi reported:
Just got evacuated from Harvard Yard due to bomb threat. Lots of police with guns out.
On its Emergency page, Harvard reports:
Recently, the Harvard University Police Department (HUPD) received a call from an unidentified male who claimed to be on campus and armed and that he had placed bombs at several buildings on Harvard's campus. HUPD officers immediately responded to the locations he identified but could not locate an individual. The named buildings -- including the Science Center -- were immediately evacuated. Cambridge Police Department and Cambridge Fire Department were notified and, with HUPD, are in the process of examining the named buildings.
Meanwhile, some Twitter rando started posting he was the one who called in the bomb threat - at least, until he thought better of it and deleted the tweets, which, of course, somebody captured first.