29 September 2010 Last updated at 10:52 ET

Gunman kills himself after firing at Texas university

Director of Communication Rhonda Weldon: ''We are asking everyone to stay off campus''

A university student killed himself after opening fire with an AK-47 assault rifle in the University of Texas library in the US city of Austin.

The man fired a number of rounds in the Perry-Castaneda Library, without harming anyone, and subsequently committed suicide, police said.

Authorities concluded their search for a second suspect after several hours, saying the gunman had acted alone.

The University of Texas is attended by at least 50,000 students.

Authorities identified the gunman as 19-year-old Colton Tooley, a second year mathematics student.

Campus police chief Robert Dahlstrom said officials had initially believed there might be a second shooter because the gunman had fired shots in more than one location.

No-one else was hurt when the gunman opened fire on the sixth floor of the school's library, university spokeswoman Rhonda Weldon said.

"He subsequently shot himself. He is deceased," Ms Weldon said.

Student Robby Reeb told ABC News he was on his way to class when a person sprinted past him saying they had seen a man with a gun.

"I looked up and saw a man in a ski mask, wearing a suit, and carrying an assault rifle. And I called 911," Mr Reeb said, referring to the emergency service telephone number.

Adjunct law professor Randall Wilhite told the Associated Press news agency he had been driving to class when he saw students "scrambling behind wastebaskets, trees and monuments" and a young man sprinting along the street with a rifle.

"He was running right in front of me - and he shot what I thought were three more shots - not at me. In my direction, but not at me, clearly not at me," Mr Wilhite said.

Campus law enforcement officers, Austin police and the state Department of Public Safety responded to the incident.

Campus alerts

The university updated students and staff via text message and e-mail throughout the morning.

"A suspected shooter in PCL library is dead. Police are searching for possible second shooter. Lock doors, do not leave your building," the university said an earlier e-mail alert.

Texas University professor Juan Garcia told CNN he had received his first text message from the university about the gunfire at 0843 local time (1343 GMT).

Mr Garcia said students used Twitter and Facebook to communicate about the incident.

The authorities are now investigating what prompted the gunman's actions.

The shooting on Tuesday is the not the first for the University of Texas.

On 1 August 1966, a shooter killed 16 people and wounded nearly three dozen from the 28th floor of the university clock tower, before being killed by police.