The deceased, a female, may have died from a self-inflicted gunshot wound but that is still under investigation, San Bruno Police Chief Ed Barberini told reporters Tuesday afternoon.
Democratic Rep. Jackie Speier, whose district includes YouTube’s headquarters, tweeted that the country must take action to end gun violence.
“I am shocked and saddened to hear about another mass shooting, this one at YouTube in my District. I am following developments and am sending prayers to the victims and survivors. We must take action and #EndGunViolence,” she tweeted.
Democratic Sen. Dianne Feinstein also tweeted about the shooting.
“My stomach sinks with yet another active shooter alert. I’m praying for the safety of everyone at YouTube headquarters,” she tweeted.
Sen. Kamala Harris, also a Democrat, tweeted that she was grateful to the first responders.
“Actively monitoring the shooting incident at YouTube in San Bruno. Grateful to law enforcement and first responders on the scene,” she tweeted.
CNN has reached out to the lawmakers’ offices for additional details on the shooting and has not yet received a response.
This story has been updated.