A student bent on confronting a teacher opened fire with a shotgun at a Colorado high school on Friday, severely wounding a classmate before taking his own life in a burst of violence possibly fueled by revenge, law enforcement officials said.
The student entered Arapahoe High School in a Denver suburb around midday brandishing the gun. He asked fellow students about the location of the teacher, then shot a 15-year-old girl who was nearby, said Arapahoe County Sheriff Grayson Robinson.
The targeted teacher immediately fled the school and was not injured, while the gunman was later found inside a classroom, dead of an apparently self-inflicted gunshot wound, Robinson said. The incident was over in 14 minutes.
"I believe the shooter knew that deputy sheriffs were immediately about to engage him, and I believe that shooter took his life because he knew that he had been found," the sheriff told a news conference.
He later named the gunman as 18-year-old Karl Pierson, who was enrolled at the school.
The rampage in the Denver suburb of Centennial took place just 8 miles (13 km) from the scene of one of the deadliest school massacres in U.S. history, Columbine High School, where two students gunned down 13 classmates and staff before killing themselves in 1999.
Robinson said there was no sign the incident was related to the anniversary on Saturday of last year's shooting at an elementary school in Newtown, Connecticut, in which a gunman massacred 20 children and six adults before killing himself.
Holly Schaefer, an 18-year-old senior at Arapahoe High School, said she was in mathematics class when she and fellow students heard a loud bang. That was followed shortly by another bang and "then we knew definitely it was a gunshot."
Schaefer said her teacher immediately locked the door to the classroom as students huddled in a corner of the room.
After about 30 minutes, Schaefer said, they heard police calling out on the other side of the door. Officers eventually cleared the classroom and as students were being escorted out of the building, she said she saw blood on the hallway floor.
Classmates speaking to CNN described the suspected shooter, who they said was a member of the school's track team and debate club, as smart and likeable. They said they would not have guessed that he was capable of such violence.
The sheriff said detectives were investigating "revenge" as a possible motive, but did not elaborate. He said investigators believed the youth had acted alone.
The local ABC News affiliate in Denver reported the suspected gunman was upset after recently being kicked off the debate squad. Reuters could not immediately confirm that report.
Arapahoe senior Frank Woronoff told CNN the gunman had recently been "demoted" on the debate team and that the teacher he was said to be targeting was its faculty adviser and the school's librarian. "I'm told that's what led him to sort of snap," Woronoff said.
Reuters was unable to contact the faculty member, who was not identified by authorities, but was named in local media reports.
Authorities said they planned to conduct searches of the suspected gunman's vehicle, which was left parked at the school, as well as two homes owned by his parents.
Colorado Governor John Hickenlooper, who pushed through tougher firearms legislation this year following the Newtown shooting and last year's attack in a Colorado movie theater that left 12 people dead, called the shooting an "all-too-familiar sequence, where you have gunshots and parents racing to the school and unspeakable horror in a place of learning."
'WE WERE FEAKING OUT'
Television images from the high school in the immediate aftermath of the shooting showed students running out with their hands raised and gathering on a track field.
Nearby businesses were evacuated as dozens of police descended on the scene with guns drawn. Authorities never fired their weapons as they pursued the gunman and then methodically evacuated the school.
Whitney Riley, 15, told CNN that she and several other students and teachers hid in a utility room after hearing gunfire and did not come out until police arrived.
"We were shaking. We were crying. We were freaking out. I had a girl biting my arm," she said. "We stayed quiet and we heard a whole bunch of sounds. We heard people yelling. We heard walkie-talkies."
The 15-year-old girl who was wounded by gunfire in the shooting was in critical condition at a local hospital following surgery, the sheriff said. There was no indication she was specifically targeted.
He said a second female student who was at first believed to have suffered a minor gunshot wound turned out to have merely been spattered with blood from the girl who was critically wounded.
Three students were also treated for what he called "anxiety attacks" - one of them at a local hospital - but all three had been released to their parents, the sheriff said.
He said a Molotov cocktail-like incendiary device was detonated inside the school by the suspect, but a second such device did not go off and was rendered harmless by authorities.