The San Bruno Police department has confirmed it’s responding to an active shooter at the YouTube Campus just outside of San Francisco. “We are responding to an active shooter,” it said via its Twitter account. “Please stay away from Cherry Ave & Bay Hill Drive.”

“Re: YouTube situation, we are coordinating with authorities and will provide official information here from Google and YouTube as it becomes available,” Google said via its official communications Twitter account.

The situation is ongoing, but YouTube employees and those in surrounding office buildings are describing the scene via social media. “Active shooter at YouTube HQ. Heard shots and saw people running while at my desk. Now barricaded inside a room with coworkers,” Vadim Lavrusik of YouTube said on Twitter. “Safe. Got evacuated. Outside now.”

Multiple other YouTube employees also tweeted about the situation.

San Bruno law enforcement officials confirmed in a press conference that at least four people have been wounded in the shooting. All are in hospitals getting treatment for gunshot related wounds. There are no fatalities at this time. All four are in hospitals and San Francisco General officials confirmed in a press conference it has three of the victims. One is in critical condition, the other serious, and the other fair.

Law enforcement also confirmed that officers are still clearing the building, but found a woman dead, apparently from a self-inflicted gunshot wound, who they believe to be the shooter.