UPDATED April 4, 12:08 a.m. ET: ABC 7 is reporting that the shooter is named Nasim Aghdam and was a disgruntled user of the platform. Aghdam was reportedly angry over YouTube's policy that demonetized channels that have less than 1,000 subscribers and 4,000 hours of watch time. Despite Aghdam's channel reportedly having over 5,000 subscribers, several of her videos were demonetized.  

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Chilling tweets have come out of YouTube HQ with reports there's an active shooter on the San Bruno, California premises. On Tuesday, YouTuber Vadim Lavrusik, tweeted that he "heard shots and saw people running," and was "barricaded in a room with coworkers" in order to stay safe.

Local law enforcement took to Twitter to mention "police activity" at the exact address of YouTube headquarters, 901 Cherry Ave. "Please stay out of the area," the tweet read.

Officers arrived on the scene 12:48 p.m. local time. There are also reports that some employees were successfully evacuated after being brought out of the building when a negotiator was sent in. 

San Bruno Police Chief Ed Barberini told reporters that four individuals were transported to the hospital with gunshot-related injuries. A spokesperson for Zuckerberg San Francisco General Hospital told CNN three of the shooting victims were admitted to the facility: a 36-year-old man who is in critical condition, a 32-year-old woman who is in serious condition, and a 27-year-old woman who is said to be in fair condition. 

Barberini also confirmed officers located a fifth victim who had died from an apparent self-inflicted wound. The chief said the deceased individual is an unidentified woman and is believed to be the suspected shooter.

No other fatalities have been reported.

Authorities have yet to confirm a motive; however, law enforcement officials told CNN the shooter may have known at least one of the victims.

President Donald Trump responded to news of the shooting via Twitter:

Google's CEO Sundar Pichai said the company is doing everything they can to provide support to the victims as well as their families: "I know a lot of you are in shock right now," he wrote in a statement. "Over the coming days, we will continue to provide support to help everyone in our Google family heal from this unimaginable tragedy."

This story is currently developing. It will be updated.