Colorado school schooting

Students, escorted by armed police, are led out of Arapahoe High School after a shooting on the campus in Centennial, Colo. (Craig F. Walker / Associated Press / December 13, 2013)

CENTENNIAL, Colo.—An 18-year-old high school student reportedly frustrated when he was ejected from the school debate club has been identified as the shooter who opened fire at a suburban Colorado high school Friday, wounding another student before killing himself.

Karl Halverson Pierson, 18, was said to be angry at the school debate coach and entered the school shortly after noon Friday with a shotgun, repeatedly calling the teacher’s name, according to interviews with students and law enforcement officials.

When he found the teacher, he “shot once and missed” before the teacher fled, according to senior Frank Woronoff, 18, who talked with the instructor—who seemed shell-shocked afterward—outside the school as students fled for safety.

“He could barely speak. All he could say were the same statements over and over. He seemed like he might have a panic attack,” Woronoff said of the teacher, whose name has not been released by authorities.

Contrary to earlier reports, there was only one gunshot victim, a 15-year-old girl, Arapahoe County Sheriff Grayson Robinson told reporters. “There’s no reason to believe she was a target,” the sheriff said, adding that it was unclear whether the girl had tried to confront the shooter.

A second girl was mistakenly thought to have been shot, but she had blood on her only because she had come into contact with the injured girl, Robinson said.

The wounded student remained in critical condition in a local hospital. The rest of the high school was evacuated earlier Friday, with students filing out with arms raised—a chilling image reminiscent of other school shootings.

The shooting in Centennial, a city of about 100,000 not far from Denver, reminded many of the deadly 1999 attack at nearby Columbine High School in which two students killed a dozen classmates and a teacher.

This latest shooting also comes as the nation prepares to commemorate the first anniversary Saturday of the massacre at Sandy Hook Elementary School in Newtown, Conn., where 20 children and six educators were killed by a lone gunman before he committed suicide.

Investigators said they recovered two Molotov cocktails after Friday’s shooting, one of which had detonated, but said it was not yet known who owned the shotgun used in the assault or when it was purchased.

Authorities will execute search warrants on three locations — the home where Pierson lived with his mother, his father’s home in Denver and Pierson’s car, which is still in the school’s west parking lot, police said.

Robinson said authorities hoped information gleaned from the searches “will help us put the pieces together.”

Friends described Pierson as an intelligent, likeable youth who liked to talk about politics and was a strong advocate of gun rights, though they said they had never seen him with a gun.

“I had class with him and knew he was very outspoken and willing to contribute, and also that he had a controlled temper he would use during discussion,” Carl Schmidt, a fellow senior, told The Times in a Facebook message.

Pierson had friends, a younger sister and a middle-class family. He was “slightly geeky,” Woronoff said, but not a loner. He attended school dances and competed at track meets. “He was one of the nicest, most down-to-earth kids I knew.”

But he was picked on.

“The kids at school knew how to push his buttons,” Woronoff said. “He was bullied a bit, but he didn’t stop. He’d get right back up.”

Though Pierson had “a multitude of friends,” Schmidt said, “only those that could cope with his personality became close with him.”

Pierson appeared to care passionately about debate, and became upset over a disagreement with the debate coach, friends said.

Joe Redmond, also a fellow senior and one of three co-captains of the debate team, said Pierson was kicked off the team and suspended from school in September for a few weeks after threatening the coach.