Facebook Inc (NASDAQ:FB) had to temporarily evacuate their headquarters in northern California due to a threat, which was later found to be a false alarm. Menlo Park police Commander Dave Bertini said that Facebook had to lock down its campus on Tuesday night after San Francisco police passed a report of a threat after 7PM. Employees were allowed to leave at 8:30PM. Over 6,000 people work at Facebook, but it is unknown how many people were at the headquarters during that time. Facebook reported this month that it would be hiring a full-time police officer to monitor its headquarters along with other local businesses.