An active shooter was reported at YouTube’s headquarters in San Bruno, Calif., Tuesday afternoon, according to social media postings from YouTube employees inside the building.
The San Bruno Police Department confirmed on its Twitter account that it was responding to an active shooter in an area just outside of YouTube’s facilities. It has not yet confirmed to TIME whether a shooter was actually inside YouTube’s headquarters.
Google, the parent company of YouTube, addressed the incident in a statement on its communications account. “Re: YouTube situation, we are coordinating with authorities and will provide official information here from Google and YouTube as it becomes available,” Google said.
According to a spokesperson, Zuckerberg San Francisco General Hospital has admitted patients from the YouTube incident, NBC News reports.
Vadim Lavrusik, a product manager at YouTube headquarters according to his LinkedIn and verified Twitter account, said just before 4 p.m. E.T. that he “heard shots and saw people running while at my desk.” Lavrusik added that he was “barricaded inside a room with coworkers” before later tweeting that he was evacuated and safe.
Todd Sherman, another product manager at YouTube HQ according to his LinkedIn and Twitter, quoted Lavrusik’s tweet, writing, “We were sitting in a meeting and then we heard people running because it was rumbling the floor. First thought was earthquake.”
“We headed towards the exit and then saw more people and someone said that there was a person with a gun,” Sherman added in another tweet, before writing, “I looked down and saw blood drips on the floor and stairs. Peaked around for threats and then we headed downstairs and out the front.”
One Twitter user posted an image of what appears to be people outside of the YouTube building with their hands up.
TIME has reached out to Google and will update when it responds. This story is developing.