Law enforcement officials in San Bruno, California confirmed that at least four people were injured after a shooter, believed to be a woman, opened fire at YouTube's headquarters Tuesday, before apparently killing herself.
"Multiple patients" were hospitalized following the reported shooting, as YouTube employees recalled seeing "blood drips on the floor and stairs" and mistaking the stampede of people exiting the building for an "earthquake."
President Trump tweeted that he was briefed on the situation, thanked law enforcement officials and first responders and noted that"Our thoughts and prayers are with everybody involved."
Lawmakers and politicians, among others, have reacted to the shooting.
Vice President Mike Pence said he's "Praying for the injured & their families. Grateful to ATF and all law enforcement & first responders who responded today and have been on the scene."
Sen. Dianne Feinstein, D-Calif., wrote on Twitter that her "stomach sinks with yet another active shooter alert. I'm praying for the safety of everyone at YouTube headquarters."
"My staff & I are closely following developments from the active shooter situation at YouTube HQ in San Bruno, CA," House Minority Leader Nancy Pelosi tweeted. "Thank you to our heroic first responders. Our Bay Area community – and all American communities – deserve real action to #EndGunViolence."
March For Our Lives, the gun reform movement created by the survivors of the Parkland, Florida, high school shooting wrote: "No one should have to fear for their lives in our free nation. No one should have to send a last 'I love you' text before returning to their hiding spot while an active shooter terrorizes their community."
Apple CEO Tim Cook tweeted that Apple employees send their "sympathy and support to the team at YouTube and Google, especially the victims and their families."
"All of us at Twitter are horrified by the shooting today at @YouTube HQ. Our thoughts and deepest sympathies are with our friends and colleagues in San Bruno," Twitter wrote.
"We are wishing all our very best for the injured and all those affected," Amazon CEO Jeff Bezos tweeted, adding that today is "horrible and truly tragic" for both YouTube and Google.