'Multiple victims' in school shooting near Los Angeles

California police were hunting a gunman Thursday after a shooting broke out at a high school north of Los Angeles, with "multiple victims" confirmed.

"This is an active shooter situation," the local sheriff's department tweeted, as police and ambulances swarmed the area around Saugus High School in Santa Clarita, 40 miles (65 kilometers) north of Los Angeles.

It said the suspect, described as a male Asian with black clothing, was still on the run.

The city of Santa Clarita tweeted that there were "multiple victims injured" in the early-morning shooting.

Police spokesman Bob Boese, speaking on the local NBC news channel, said there were "at least three" victims but cautioned that it was not clear if all victims had been located.

"Our deputies are doing a systematic search of the campus, still looking for the suspect," Boese said. He said one weapon had so far been recovered.

No official details were immediately available on the condition of the victims. Aerial video from the NBC affiliate showed students with hands raised being escorted by officers from the building, and led to a nearby church, as others stood outside the perimeter on their cell phones.

At least three ambulances were at the school campus, opposite a residential area, along with dozens of squad cars.

Agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were among those responding to the scene.

The Santa Clarita Valley Sheriff's department warned residents to stay clear of the area.

"If you live in neighbourhood anywhere near Saugus High, PLEASE LOCK DOORS and stay inside," it tweeted.