Florida State University police shot and killed a gunman who had opened fire in the crowded university library around midnight. Three people were wounded.

Michael DeLeo, Tallahassee, Fla.'s chief of police, said the gunman appears to have acted alone.

"It will take not only hours but days to put all the pieces together," he said at a news conference this morning. "Obviously, everyone wants to know why, and that's the hard question that we're going to continue to investigate and try to find those answers for everybody."

Hundreds of students who were in the library studying for final exams at the time fled or took cover as the gunman began firing. David Northway, a spokesman for the Tallahassee Police Department, said police were called to the scene shortly after midnight. They confronted the gunman in front of the Strozier Library and ordered him to drop his weapon. The gunman, Northway said, shot at one of the officers. Police returned fire, killing the suspect, Northway said.

Northway said police were collecting forensics and questioning witnesses who were at the scene.

"This will go on for hours," he said.

FSU Police Department Chief David Perry said the campus-notification system worked well, and students on campus were alerted to the gunman's presence. At about 4 a.m., an "all clear" was sounded around campus, and students holed up in the library were then allowed to return home. Perry said security was being tightened on campus following the incident. Classes were canceled for Thursday.

Students who witnessed the shooting described chaos.

John Ehab, a sophomore from Tampa, Fla., told The Associated Press he was on the library's third floor when he heard multiple gunshots.

"Everyone heard them," he said.

He said those in the library took cover in the book aisles.

Allison Kope, a freshman from Cocoa Beach, Fla., said she was on the library's first floor when she heard a loud noise. People began screaming about a gunman, she told the AP.

"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 told the agency. "I ran right out the back door. 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."

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