WASHINGTON, Nov. 29 (Xinhua) -- One suspect attacker was killed by police Monday after he plowed his car into pedestrians on the Ohio State University (OSU) campus and swung knife to stab them, leaving 11 people injured.

The injured people, most of whom were in stable condition, were being treated in local hospitals.

The suspect drove a car into a group of pedestrians on the sidewalk and then stepped out of the car and began stabbing people with a butcher knife, police reports said.

An OSU student who witnessed the incident said that he initially thought it was a car accident when a vehicle rammed into passersby, until the driver came out with a knife in hand.

The attacker was shot in less than a minute by university police officer Alan Horujko, who was nearby investigating an earlier report of gas leak, OSU Police Chief Craig Stone said.

OSU Department of Public Safety Director Monica Moll identified the attacker as OSU student Abdul Artan, who was born in Somalia and living in the United States as a legal permanent resident.

The motive behind the attack remains unclear. Columbus Police Chief Kim Jacobs said they were considering the possibility of a terrorist attack.

At least two people were wounded by knife and four others were injured by the car, university officials said, while Ohio Governor John Kasich said full recovery is expected for all those injured.

Earlier, OSU's official twitter account sent out a warning message, reading "active shooter on campus. Run hide fight. Watts Hall. 19th and College."

It was later clarified that the gun shots were fired by the police.

"Run, hide, fight" is a standard protocol for active shooter situations. It means: Run, evacuate if possible; hide, get silently out of view; or fight, as a last resort, take action to disrupt or incapacitate the shooter if your life is in imminent danger.

The school also put out a shelter-in-place warning, asking students to seek safety within buildings they have already occupied.

The warning was retracted later after about an hour and half when the police determined the sole attacker was killed.

OSU later announced that all classes were canceled for the rest of the day.

OSU, one of the largest U.S. universities, has nearly 60,000 students on its Columbus campus.