At least eight people were injured Monday in an apparent shooting at Ohio State University, officials said, with the Columbus campus still on lockdown.
Law enforcement shot and killed one suspect, according to local television station WBNS, which said there were unconfirmed reports of a second shooter involved.
Rebecca Diehm, spokeswoman for the Columbus Division of Fire, said eight people had been transported to hospital.
One was in critical condition, and the rest were stable, she said. There were no details on the exact nature of their injuries.
The university's emergency management service urged students and staff to shelter in place, as SWAT teams fanned out across the facility.
"Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College," the service said in a tweet.
A second tweet moment later told the public to "Continue to shelter in place. Avoid area of College."
Details were murky as the situation unfolded. One student told MSNBC she was walking along a road on campus when a car plowed into a group of people, including a police officer.
It was not immediately clear how that was connected to the apparent shooting.
Student Cydney Ireland told ABC she was walking out of class when she heard screams.
"And then after that -- which this is kind of strange -- there was a whistle almost like a referee whistle. I wondered if a sports team was practicing. That's kind of an unusual thing to hear in the academic area," she said.
"Probably five seconds after that there were three gunshots."
"Everybody was running in any direction they possibly could, students were running out of the classroom building," she said from her hiding spot in a locked bathroom.
Ohio State is one of the largest universities in the United States, with roughly 60,000 students on the main campus in Columbus with sprawls across more than 1,900 acres (770 hectares).