Two people are dead and six others are in hospital after a shooting on Thursday at Florida State University in Tallahassee.
The deceased were not students, police said.
Leon County Sheriff Walter McNeil said the alleged shooter is a 20-year-old man. Mr McNeil said he is the son of an officer with the force and one of the guns found at the scene belonged to the officer.
President Donald Trump said he had been briefed on the incident at the start of a meeting with Italian Prime Minister Giorgia Meloni at the White House, calling it “a shame, a horrible thing”.
Florida Governor Ron DeSantis said: “Our prayers are with our FSU family and state law enforcement is actively responding.”
The university has cancelled all classes until at least Friday, and sports events were also cancelled for the weekend.
Police responded to an active shooter call at around midday local time, the university said.
An alert was issued soon after warning students and those on campus to “seek shelter and await further instructions”.
“One of my classmates got an alert on her phone and announced it to the rest of the class,” student Ava Arenado told CBS News Miami.
Another student, Blake Leonard, told CBS that he initially heard about 12 shots fired.
“In my head I thought it was construction at first, until I looked behind me and saw people running from the union towards my direction, and then I heard another 12 or 15 shots go off, so I started running away from there too,” he said.
This is not the first shooting at Florida State University in recent years. In 2015, a graduate of the school shot and injured three people at the library before he was fatally shot by police.