An Ohio State student drove a speeding car into a crowd outside a classroom building Monday morning, then got out and slashed at people with a large knife.
Abdul Razak Ali Artan, 18, rammed his car into a group of pedestrians on campus then got out and began stabbing people before police shot him dead.
Police Chief Kim Jacobs said they were investigating whether it was a terrorist attack.
Somali-born Artan was living in the US as a legal permanent resident, unnamed officials told AP news agency.
Law enforcement officials quoted by NBC News said the attacker had left Somalia with his family in 2007, and lived in Pakistan before resettling two years ago in the US.
Asked at a news conference whether it could have been a terrorist act, Police Chief Jacobs said: "I think we have to consider that it is."
Columbus Fire Department confirmed that at least nine people have been brought to hospital after the suspect deliberately ran in to people and attacked them with a butcher's knife.
One person is said to be in a critical condition.
The university initially tweeted about the incident, urging students to "run, hide and fight". OSU remains on lockdown.
Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College.
— OSU Emergency Mngmnt (@OSU_EMFP) November 28, 2016
PHOTO: Students barricade door to classroom amid incident at Ohio State University. https://t.co/KGuP6ey7OI pic.twitter.com/RFWdypDjCt
— ABC News (@ABC) November 28, 2016
Facebook released a Safety Check feature for the incident, allowing people in the area to mark themselves as unharmed.
University police said the shelter-in-place order was lifted and that the "scene was secure". All academic classes on campus have been cancelled for the day.
With nearly 60,000 students at its main Columbus campus, Ohio State is one of America's largest universities.
