CENTENNIAL, Colo. — The teen gunman who shot himself dead after critically wounding a fellow student at their suburban Denver high school apparently acted in retaliation for discipline leveled against him by the school’s debate club coach, the county sheriff said on Saturday.
Sheriff Grayson Robinson also said that 18-year-old Karl Pierson legally purchased the shotgun and ammunition he used in Friday’s rampage at Arapahoe High School. The sheriff said the attack lasted less than a minute and a half.
Police said the student gunman’s intended target appeared to be a teacher who Pierson was calling out for by name as the armed teenager stalked through the hallways of Arapahoe High School.
The faculty member, who police have not publicly named but who local media accounts, citing eyewitnesses, have identified as school librarian Tracy Murphy, fled the building unharmed.
When the suspect started shooting, a 15-year-old girl, who authorities say was in Pierson’s line of fire though apparently not an intended victim, was severely wounded.
A second girl who was initially thought to have been wounded was not injured, but spattered with blood from the teenager who was hit as staff and students scurried for cover.
Sheriff’s deputies and police converging on the school encountered heavy smoke in the building from a Molotov cocktail-like incendiary device Pierson had set off, one of two he was carrying.
Pierson, who had entered the school brandishing a shotgun, was found by police about 15 minutes later in a classroom, dead from a self-inflicted gunshot wound, the sheriff said.
Robinson said the teen appeared to have killed himself as law enforcement officers closed in, though officers never fired a shot.
The wounded girl, who has not been publicly identified, remained listed in critical condition at nearby Littleton Adventist Hospital, where she underwent surgery, a hospital spokeswoman said.
Authorities have not disclosed the nature of her injuries, but an account in the Denver Post cited radio transmissions from the first deputy on the scene, who reported finding a student with a “bad head injury” moments after the shooting began.
The violence on Friday unfolded just 8 miles from Columbine High School, where a pair of students shot 13 classmates and staff to death before killing themselves in 1999.
It also came on the eve of the one-year anniversary of the Sandy Hook Elementary School massacre in Newtown, Conn., in which a gunman killed 20 first-graders and six adults before taking his own life.
So far this year, there have been 28 shootings on U.S. school grounds during school hours, including Friday’s incident at Arapahoe High, according to a tally kept by the gun control advocacy groups Mayors Against Illegal Guns and Moms Demand Action for Gun Sense.
In Friday’s shooting, fellow students described Pierson as a smart and likable member of the school’s track team and debate club. Police said they knew of no prior threats or discipline problems by Pierson, though some students recalled him as having a combative personality.
Classmate Max Minne told Denver’s ABC News affiliate that Pierson was “verbally aggressive” and had been sent to the administration office earlier in the week for yelling at a teacher because he thought he had been locked out of a class.
Authorities said they planned to search the suspected gunman’s vehicle, which was left parked at the school, and two homes owned by his parents.
The local ABC News affiliate reported Pierson was upset after being kicked off the debate squad.
Arapahoe High 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.