Police arrived on the scene where they found four injured victims and one person dead with what police believe was a self-inflicted gunshot wound.
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Evacuations quickly began for workers on campus, who walked out of the building with their hands raised.
Watch the video in the player above for the full story from Dion Lim.
KEEP SCROLLING: Full coverage on the YouTube shooting
VIDEO: Aerial footage shows active shooting situation at YouTube HQ
Video of the scene at YouTube headquarters in San Bruno, Calif.
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