'I saw blood drips on the floor and stairs': YouTube eyewitness on active shooter incident

'Every new person I saw was a potential shooter', he writes

A YouTube product manager has described the terrifying scene at a shooting at California headquarters of the social media company, which reportedly ended in dozens of people being rushed to the hospital.

Todd Sherman, a YouTube product manager, said on Twitter that he was in a meeting when he got his first indication that something was wrong: The sound of people running down the hall. At first, he thought the noise was an earthquake.

“After existing the room we still didn’t know what was going on but more people were running,” he wrote. “Seemed serious and not like a drill.”

But as he headed towards the exit, Mr Sherman realised the situation was more dire. He heard someone say there was a person inside with a gun. Another person said someone had shot out the back doors and then shot themselves.

“At that point every new person I saw was a potential shooter,” he wrote.

Making his way to the exit, Mr Sherman said he saw blood on the floors and stairs. He looked around for potential threats, then headed down to the ground floor. Outside, police cruisers were pulling up with rifles at the ready.

Footage posted to Snapchat from close to the San Mateo campus showed police in tactical gear surrounding the building. Employees walked out with their hands above their heads.

Mr Sherman said he informed the police of what he had seen, then walked down the street to meet coworkers. He ordered an Uber to get home.

“In an Uber omw home,” he tweeted. “Hope everyone is safe.”

At least two hospitals have confirmed that they received patients injured in the shooting, though it is not known exactly how many.