A gunman opened fire this morning at a University of Texas library that resulted in the death of the shooter by his own hand, authorities said. Police believe the shooter was a UT student; however, they are still awaiting confirmation from the medical examiner's office, the Austin-American Statesman is reporting.

Shortly after 8 a.m., Colton Tooley, a 19-year-old sophomore majoring in math at UT, entered the school's Perry-Castaneda Library and allegedly fired four shots with an AK-47 rifle. The suspect, who was wearing black clothing, then headed to the sixth floor, where he shot himself, Gary Susswein, a university spokesman, tells POLICE Magazine.

"No one else was injured in the gunfire," Susswein said.

The university was immediately placed on lockdown, meaning students, faculty, staff and visitors could not leave. An alert system, including an emergency siren, loud speaker, emergency text messages and online communications informed the UT community of the incident.

The Austin Police Department's SWAT unit arrived at the scene with an armored rescue vehicle to help secure the perimeter and provide assistance to university police officials in searching for a second suspect, according to a department spokeswoman.

At around noon local time, the campus lifted the lockdown, and closed the campus, cancelling all classes.

Austin Police Chief Art Acevedo told the Houston Chronicle police are investigating two crime scenes - the library and a second location where "some rounds were fired outdoors."

Two students were treated for minor injuries that appeared to have happened while they were evacuating, reports Statesman.com. Shuttle buses transported students off campus during the incident.

Initially, police believed a second gunman was involved in the incident because of differing descriptions of the shooter, according to MSNBC.com . However, officials do not believe there is a second suspect.

Sophomore Dan Culpepper said the gunman did not seem as if he wanted to hurt anyone because he had the opportunity to shoot others, but chose not to. Watch his interview with the Houston Chronicle below.

Perhaps the university's most well-remembered shooting occurred on Aug. 1, 1966, when student and ex-Marine Charles Whitman went to the 28th floor observation deck at the UT clock tower and began shooting at people below. He killed 14 people and wounded 32 others before police killed him about 90 minutes after the siege began.