(AP) - Florida State University police fatally shot a gunman at the campus library early Thursday in 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.

Hours after the shooting, detectives could be seen inspecting the body of the suspected gunman, who was lying face down at the top of an access ramp just outside the library. A gray baseball cap lay near his head.

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.

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.

Allison Kope, a freshman from Cocoa Beach, said she was on the library's first floor when said she heard a loud noise and then there was a lot of commotion. She said people were screaming about a gunman and chairs started flipping over.

"You never think something like this is going to happen to you until you have to react in that situation when someone is screaming there is a gun in the building. I ran for my life," she said. "I ran right out the backdoor. My laptop and everything is still in there. It was shock. It was just instinct. You don't think about anything else, you just go."

Daniel Morales, a 19-year-old freshman from Fort Pierce, said that when he first heard someone say "somebody's got a gun. I thought he was joking." But after realizing there was a gunman in the library, Morales and others raced to a back room on the second floor where they barricaded a door with desks.

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."

Florida State President John Thrasher, who took office earlier this month, said by phone that he was in New York City and had no first-hand information. He said he was making arrangements to hurry back to Tallahassee.

Thrasher decided to cancel classes Thursday for the entire campus, although the university itself would remain open.