COLUMBUS, Ohio -- Police are releasing 911 calls made as the attack unfolded Monday at The Ohio State University.
Abdul Razak Ali Artan, a student who recently transferred to OSU, rammed his car into a group of people on the campus and then got out and charged at passersby with a butcher knife.
Ohio State University Police Officer Alan Horujko shot Artan after he failed to obey orders to stop -- killing him and stopping the attack.
A total of 11 people were injured in the attack. Seven have been discharged from the hospital. Four others are still hospitalized in fair condition.
Investigators are searching for a motive behind the knife attack.
The 911 calls released Tuesday were made by witnesses and emergency responders.
In one, an Ohio State University official told the dispatcher that there was "one down."
"This is OSU," said the caller. "We have a vehicle that struck several pedestrians. We have gunshots fired. We have one down."
In another call, the caller said he was with a student who'd been stabbed in the arm during the ordeal. He said a group of people had wrapped their coats around her arm to help stop the bleeding.
In other 911 calls to police, several students described the chaotic scene.
"I think this is some type of terrorist attack," said one caller, according to CNN affiliate WCMH. "Because the guy ran a car through a crowd of students. The guy did it purposefully."
The attack lasted less than two minutes.
About 90 minutes after the first 911 call came in, a campus lockdown was lifted.
Students had just returned to class Monday after Thanksgiving break.