Facebook personnel held employees at the campus until
officers were on scene, Menlo Park Police Department spokesman
Dave Bertini said. Police officers allowed Facebook staff to
leave at about 8:30 p.m. (0330 GMT).
"It was a totally not credible, unsubstantiated threat," Bertini
said, though he declined to say what the specific threat was. "I
am not even sure that it was specifically to the Menlo Park
campus of Facebook."
Facebook declined to comment on the incident.
The San Francisco Police Department did not immediately respond
to requests for comment.
(Reporting by Eric M. Johnson in Seattle;
editing by Louise
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