Florida State University police fatally shot a gunman at the campus library early Thursday after a shooting that left three students wounded as hundreds studying inside the library fled or took cover in panic.
Officers confronted the gunman and ordered him to drop his weapon, but he fired one shot at them and they unleashed a volley of shots, Tallahassee Police spokesman Dave Northway said.
While police did not say if the wounded were shot by the gunman, senior Sarah Evans, from Miami, said she was inside the library and heard a male student say he had been shot.
When she looked at him, he was on the ground with blood spreading on his pants leg.
Northway said authorities did not believe there were any other threats related to the incident. Shortly after 4 a.m., a loud tone sounded across the campus followed by an announcement that the campus was "all clear."
At the same time, authorities allowed hundreds of students who had been shepherded in a classroom building next to Strozier Library, a multistory building in the center of the Tallahassee campus, to return to their homes or the library to retrieve possessions they left behind in their rush to escape.
University officials said classes are canceled Thursday, though the campus is open. The library will be closed until further notice.
Police said it the shooting appeared to be an isolated incident.
There was no immediate word on what prompted it.
School officials said all three victims are students. It was unclear whether the gunman also was.
Some shots were fired inside the library and some outside, police said.
A local hospital, Tallahassee Memorial HealthCare, told CBS News at least two victims were brought there. The hospital said one victim was in critical condition and the other in stable condition.
The third victim was only grazed and was treated and released at the scene, police said.
CBS Tallahassee affiliate WCTV reports the shooting happened just after midnight.
Earlier, the school warned students of a "dangerous situation" on campus. The message said, "*FSU ALERT!* Dangerous Situation! Main Campus - Tallahassee. Seek shelter immediately, away from doors and windows."
Students who had been in the library described a chaotic scene where they heard shots, followed by students either barricading themselves in parts of the library or taking cover.
WCTV quotes a student who lives close to the library as saying "several gunshots right in a row" were heard.
John Ehab, a sophomore from Tampa, said he was on the library's third floor when he heard multiple gunshots.
"Everyone heard them," he said. People took cover in the book aisles to hide from the gunman in case he came onto the floor, Ehab said.
Freshman Nikolai Hernandez said he was in his dorm room across from the library when he heard five or six rapid gunshots.
"It was a consecutive bop, bop, bop, bop, bop," Hernandez said. "It makes me definitely a little bit nervous. I was supposed to be in the library. I had a paper to do and I got a little bit lazy and decided not to do it."
He said he has friends still locked inside the library two hours after the shooting.
A campus telephone alert urged people to take shelter in a nearby building and stay away from doors and windows. Campus and Tallahassee police declined comment.
Florida State President John Thrasher, who took office earlier this month, said by phone that he is in New York City and had no first-hand information. He said he was making arrangements to hurry back to Tallahassee.
In a sign campus life was returning to a semblance of normalcy, workers at a doughnut shop near the library had begun cooking doughnuts for the morning rush, the smell wafting over the scene.