Police officers stand guard near the headquarters of YouTube in San Bruno, California, the United States, April 3, 2018. Police in north California are responding to a reported shooting at the headquarters of the world's largest online video network YouTube Tuesday afternoon, authorities said. (Xinhua/Wu Xiaoling)

SAN FRANCISCO, April 3 (Xinhua) -- Police in north California are responding to a reported shooting at the headquarters of the world's largest online video network YouTube Tuesday afternoon, authorities said.

"The ATF San Francisco Field Division is responding to a reported shooting at YouTube headquarters in San Bruno, Calif.," the Bureau of Alcohol, Tobacco, Firearms and Explosives @AFTHQ tweeted.

Police in San Bruno, about 19 kilometers south of downtown San Francisco on U.S. western coast, also warned on their official Twitter account that people should "stay out of the area" because of "police activity at 901 Cherry Ave" near the YouTube headquarters.

Twitter user Vadim Lavrusik, who described himself as an employee of YouTube, said earlier in his Twitter page that "Active shooter at YouTube HQ. Heard shots and saw people running while at my desk. Now barricaded inside a room with coworkers."

TV helicopter video showed that people were going out of a building with their hands up.

San Bruno police said they could not provide more information right now.