Seven people have been taken to hospital after reports of a shooting incident at Ohio State University, the Columbus Fire Department has said.
The department added that two of those people are in stable condition. It had no information on the other five people.
Ohio State University warned students in a series of tweets on Monday morning that there was an active shooter on campus and that they should "run, hide or fight".
Watts Hall is a materials science and engineering building. The university followed up with another tweet.
The university also asked for anyone with information to call police.
"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.
A Columbus police dispatcher declined to comment on the reports, but police vehicles were seen at the scene.
With nearly 60,000 students at its main Columbus campus, Ohio State is one of the nation's largest universities.