A man plowed his car into a group of pedestrians at Ohio State University and then got out and began stabbing people with a butcher knife before he was shot and killed by an officer Monday morning, campus police said.

Nine people were hurt, one critically, and Columbus Police Chief Kim Jacobs said police were looking into whether it was a terrorist attack.

The details emerged after a morning of confusion and conflicting reports that began with the university issuing a series of tweets warning students that there was an “active shooter” on campus near the engineering building and that they should “run, hide, fight.”

Numerous police vehicles and ambulances converged on the 60,000-student campus, and authorities blocked off roads.

Ohio State Police Chief Craig Stone said that the attacker drove over a curb outside a classroom building and that an officer who was nearby shot the driver.

“The threat ended when the officer shot the suspect,” said Monica Moll, the school’s public safety director.

The shelter-in-place warning was lifted about an hour and half later and the campus was declared secure after police concluded there was no second attacker, as rumored.

At least two people were being treated for stab wounds, four were injured by the car and two others were being treated for cuts, university officials said.

Rachel LeMaster, who works in the engineering college, said a fire alarm sounded before the attack.

“There were several moments of chaos,” she said. “We barricaded ourselves like we’re supposed to since it was right outside our door and just hunkered down.”

LeMaster said she and others were eventually led outside the building and she saw a body on the ground.

Cassidie Baker, an Ohio State senior, said she saw police or paramedics helping one person on the ground outside Watts Hall, a materials science and engineering building.

“No one really knows what is happening, other than there’s an active shooter,” she said.

Classes were canceled for the rest of the day.

The initial tweet from the university’s emergency management department went out around 10 a.m. and said: “Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College.”

“Run, hide, fight” is 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.

(AP)