San Francisco, Oct 19 (IANS): A manhunt is on to nab multiple suspects involved in a San Francisco high school shootout, authorities said.

At least four teenaged students were injured, of whom one is reported to be critical.

"One 15-year-old female victim with life-threatening injuries to her upper torso was rushed to the San Francisco General Hospital," San Francisco Police Officer Carlos Manfredi told Fox News.

The San Francisco Unified School District said that the shooting was "an isolated incident outside of the school building, where one female student was targeted by outsiders", CNN News reported on Wednesday.

Students of the June Jordan School for Equity had treated the initial shots fired on Tuesday as a prank, until school officials ordered an immediate lockdown.

In the end, four students were injured in the parking lot shooting around 3.20 p.m. as they were being dismissed for the day, Manfredi said.

Investigators had launched a combing operation tracking each room inside the school building to hunt down multiple suspects.

The shooters, wearing dark hoodies and jeans, were last seen running across the parking area towards the locked-down school building.

The restrictions were, however, lifted about an hour later after the police had cleared each room.

Besides the girl victim, who appeared to be the target, all the other boys received non life-threatening injuries and were given first aid.

According to police, all four male suspects were still at large. It was unclear whether they had fled on foot or in a getaway car.

School district officials had tweeted that June Jordan high school would open for classes on Wednesday. However, they planned to have additional "support" on hand for both the students and staff.