DEVELOPING: An 18-year-old Somali man was behind an attack involving a car and butcher knife on the campus of Ohio State University Monday that left nine people injured, law enforcement sources told Fox News.

After the suspect plowed his vehicle into the crowd, officials said he got out of the vehicle and began attacking people with a butcher knife before he was shot and killed by a campus police officer.

Two law enforcement sources told Fox News the attacker, identified as Abdul Artan, came into the United States as a Somali refugee, and was granted status as a legal permanent resident.

The motive behind the attack is still unclear, according to law enforcement sources, but investigators are not ruling out anything at this point.

Ohio State Police Chief Craig Stone said the attacker purposely drove over a curb and into pedestrians.

“This was done on purpose,” he said.

Columbus Police Chief Kim Jacobs said police were looking into whether it was a terrorist attack.

Monica Moll, the school’s public safety director, told reporters the attack took place in front of Watts Hall, the location of the Department of Materials Science and Engineering, around 9:52 a.m.

A campus officer nearby engaged the suspect, who was attacking people with a butcher knife, and shot and killed him within minutes.

“The threat ended when the officer shot the suspect,” she told reporters.

Moll said that “injuries were minimized,” due to the rapid reaction of campus police.

Ohio State University said in a statement the injuries included stab wounds, and being struck by a vehicle. There were also other injuries that were being evaluated.

Jerry Kovacich, a third-year in welding engineering, told the school’s newspaper,The Lantern, that he witnessed a man in a car try to drive into a crowd of people after a fire alarm went off. After the car crashed, Kovacich told the newspaper he witnessed the man then attack bystanders with a knife.

“I didn’t see anything with the shooter, what happened was it was outside of MacQuigg Lab,” Kovacich told The Lantern. “The guy ended up just coming and hopping the curb with his car and trying to mow down a couple people. He lost control, and I think he ended up hitting three people, and then people were around the car. Somebody asked him if he was OK and the guy just hopped out of the car with a butcher knife and starting chasing people around.”

There continues to be a massive law enforcement presence on campus, including a SWAT team and officers with long guns. Police also blocked off roads around the perimeter of the campus, clogging area traffic. Classes were canceled for the rest of the day.

The school initially sent out a campuswide alert at 9:56 a.m. local time which read, “Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College.”

Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College.

UPDATE 1/2 : Shelter in Place lifted. Scene is now secure. ALL classes are canceled on Columbus campus for the remainder of the day.

Campus police tweeted the same alert, and wrote in another tweet, “Continue to shelter in place. Avoid area of College.”

By 11:30 a.m., the school announced the shelter in place was lifted, and the “scene is now secure.” All classes were canceled on the Columbus campus for the remainder of Monday.

Authorities said later that it doesn’t appear that the suspect used a gun in the attack.

Authorities initially believed there were multiple attackers, with one possibly hiding in a parking garage, but later said at a news conference they believe there was only one suspect.

Heavy police presence at the Lane Avenue Garage. Officer on scene said the remaining shooter is believed to be inside.

One student who spoke to WBNS from her hiding place in a restroom said the situation was frightening.

“I’m a little shaken up at first,” Cydney Ireland told the station. “I do feel safe based off the room I’m in.

Student locked in a bathroom describes on the phone how people ran in 'every direction'

“It’s absolutely surreal,” she said.

Rachel LeMaster, who works in the engineering college, told The Associated Press 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.

Fox News contributor Rod Wheeler, a former Washington DC homicide detective and an OSU alum, said the school’s police department is highly trained.

“People don’t need to panic,” he said, adding that those in hiding should stay put and switch their cell phones to vibrate.

A law enforcement officials tells Fox News that the FBI Columbus Field Office SWAT team has been activated, and deployed to the campus to assist local authorities with the reported active shooting.

The ATF Columbus Field Division agents are also responding to the scene, the agency tweeted.

The sprawling, 58,000-student main campus in downtown Columbus is one of the nation’s largest.

Fox News’ Jennifer Griffin, Matt Dean and The Associated Press contributed to this report.