Police are responding to an active shooter situation at YouTube’s headquarters in San Bruno, California. Employees evacuated the building and police are warning people to avoid the area. The San Mateo County

Sheriff’s Office tells CBS News it is treating the situation as an “active shooter incident” but declined to provide more details. San Francisco General Hospital tells CBS News they are preparing to receive patients. The San Bruno Police Department also confirmed they were responding to an active shooter. They asked people in the area to stay away from Cherry Ave and Bay Hill Drive. Several employees tweeted they heard gunfire Tuesday afternoon. Vadim Lavrusik said he barricaded himself and others inside a room before they were able to escape safely.

Some 1,700 people work at the YouTube HQ. Google said it was “coordinating with authorities” and would provide information as it becomes available.

Images broadcast on local TV stations showed employees leaving with their hands raised. Other footage appeared to show evacuees forming a queue before being individually frisked by police.