Police flooded Facebook's headquarters in Northern California to investigate a threat they later found wasn't credible.
Menlo Park police Commander Dave Bertini says Facebook's campus was locked down Tuesday night after San Francisco police passed along a report of a threat shortly after 7 p.m.
Bertini says the threat was found to be unsubstantiated and not credible. He would not give further details.
The area was declared safe, and employees were allowed to leave at about 8:30 p.m.
More than 6,000 people work for the social media giant, but it wasn't clear how many were at the headquarters at that hour.