The University of Texas at Austin, the site of one of the worst campus shootings in US history, came close to another tragedy Tuesday as a ski-mask wearing gunman fired several shots on campus before taking his own life. No one else was hurt.

The UT shooting comes as Texas, and UT in particular, was already at the center of a national debate over whether to allow students to carry concealed weapons to protect themselves against attack. In fact, an advocate of concealed weapons is still scheduled to address students Tuesday night.

The national debate on the issue was spurred largely by the 2007 shooting at Virginia Polytechnic Institute, in which 32 people were killed. Yet UT is also familiar with campus shootings. In 1966, a sniper shooting from UT's iconic clock tower killed 14 students.

John Woods, a graduate student at UT, has spoken out against concealed-carry laws. As an undergraduate he survived the Virginia Tech shooting, in which his then-girlfriend died. "The idea that somebody could stop a school shooting with a gun is impossible," Woods told the Associated Press during debate over a proposed campus carry law in Texas last year. "It's reactive, not preventative."

Meanwhile, a lecture by John Lott, the author of "More Guns, Less Crime," was scheduled to be delivered as planned Tuesday night, although at an off-campus location. Daniel Crocker, the Southwest regional director for Students for Concealed Carry, a pro campus-carry group, says Mr. Lott was planning to talk about "the fact that every mass shooting in the last 25 years have been in places where firearms are banned."

"Nobody wants to be Rambo or go out there to save the world, but at VT people spent nine minutes under desks hoping and praying that they didn't run out of time," says Mr. Crocker. "We don't want to be in that situation."

Texas considers law

In 2009, a campus-carry bill failed in the Texas legislature, meaning the otherwise gun-friendly state decided against joining Utah and Colorado among states that allow students to carry weapons at public universities. However, Tuesday's shooting is likely to play into the debate when it is reintroduced again next session, says Crocker.

Twenty-four states expressly forbid carrying guns on campus. As of last year, attempts in 18 states to allow students to carry guns on campus failed, according to the Brady Campaign to Prevent Gun Violence.

Supporters say campus-carry laws can help prevent tragedies like the one at Virginia Tech and the 2008 shooting at Northern Illinois University, where five were killed and 18 wounded.

"Because of gun free zone laws, everyone who was a potential victim [during Tuesday's attack] were at the mercy of a crazed gunman," says Jeff Shi, the UT campus coordinator for Students for Concealed Carry on Campus.

'Everything happens too quickly'

Opponents say that allowing guns on campus will breed unnecessary fear among classmates and professors as they face the potential of a disgruntled student pulling a gun over an argument or when faced with a bad grade.

Mr. Woods, a visible and poignant spokesman for groups that oppose campus-carry laws, fought against the Texas law last year. He told the Associated Press that he briefly considered buying a gun after the Virginia Tech shooting, carried out by Seung-Hui Cho, an undergraduate. But, ultimately, Woods said that a classroom shooting would be too sudden to stop, even if someone in the room had a gun.

"Everything happens too quickly," Woods told AP. "You either play dead or you are dead."

On Tuesday, witnesses heard several shots and one professor told reporters that he watched the gunman, who appeared to be smiling, walk by him and fire several shots his way, all of which missed. Police say the man shot himself on the sixth floor of the campus library. Police initially searched for a possible second gunman, but by noon Central time police lifted the campus lockdown and said the gunman acted alone.

Campus authorities say they sent out an email and text warning at 8 a.m., shortly after police received reports of an armed man on campus, urging students to stay in place. Students, according to news reports, credited police for their quick reaction, show of force, and rapid lockdown of the campus.