Amber Downing, Tony Plohetski and Doug Stanglin

USA TODAY

AUSTIN, Texas — A white, middle-aged gunman, in what appears to be a politically motivated anti-government attack linked to immigration, fired more than a hundred rounds at buildings in downtown Austin early Friday and tried to set fire to the Mexican consulate before he died of a gunshot wound.

Police identified the gunman as 49-year-old Larry Steven McQuilliams and said he had a criminal record. No details were immediately released about his background.

Police were investigating whether he was killed by a police officer who fired at him in front of police headquarters or died of a self-inflicted gunshot.

A police sergeant putting away police horses for the night shot the suspect with one hand while holding two horses by the reins in the other, Austin Police Chief Art Acevedo told reporters.

Between about 2:20 a.m. and 2:30 a.m. CT, McQuilliams fired at several buildings in downtown Austin, including police headquarters and the federal courthouse. He also tried to torch the Mexican consulate using several small propane cylinders, but the fires were put out before the flames could spread, Acevedo said.

After the shooting, police discovered suspicious cylinders McQuilliams' white van parked in front of the police headquarters, which was then evacuated. Officers also feared that the man's bulky vest might contain explosives and retreated after dragging the wounded suspect across the street.

A bomb squad, using a robot, found no explosives, Acevedo said. McQuilliams' Austin home was also searched, police said, KVUE-TV reports.

Acevedo said the city was particularly fortunate that no one was injured, given the normal activities in downtown on a Friday night. The attack happened near the Sixth Street entertainment district, where bars close at 2 a.m.

Police closed Interstate 35, which runs through central Austin, for three hours, and several downtown streets remained shut Friday afternoon.

The police chief said the suspect's targets indicated that he might have had anti-government motives linked to immigration.

"If you look at the targets, it doesn't take a genius (to suggest) that that is the potential," Acevedo said. "I would venture that political rhetoric might have fed into some of this, but that is speculation on my part."

"When you look at the national debate right now about immigration, that ... comes to mind. Sometimes our political discourse becomes very heated and sometimes very angry," Acevedo said.

Sen. Tom Coburn, R-Okla., warned last week that an executive order on immigration by President Obama could spark "instances of anarchy" and "violence."

Mexico's Foreign Relations Department expressed "profound concern and condemnation" of the attack, but added in its statement that "there is no evidence the shots were exclusively directed at our facility."

Amber Downing and Tony Plohetski report for KVUE-TV in Austin. Contributing: Michael Winter; the Associated Press