In this still image taken from video provided by Fox 31 Denver, students gather just outside of Arapahoe High School as police respond to reports of a shooting at the school in Centennial, Colo.
CENTENNIAL, Colo. — Authorities have identified an 18-year-old as the student who opened fire with a shotgun at a suburban Denver high school before killing himself.
Arapahoe County Sheriff Grayson Robinson identified the shooter Friday night as Karl Halverson Pierson.
The sheriff has said Pierson made no attempt to hide his weapon after entering the school from a parking lot and asking for a teacher by name.
Robinson did not elaborate on any possible motive except to say Pierson had had a “confrontation or disagreement” with the teacher.
Authorities now say Pierson shot one fellow student, not two as originally reported. The wounded 15-year-old underwent surgery and was in critical condition.
Another girl who was taken to the hospital with reported minor gunshot wounds, but the sheriff says she was covered in blood from the other student and wasn’t injured.
Authorities also found a possible Molotov cocktail at the scene and are examining the device.
The school is about 8 miles east of Columbine High School in Littleton, where two teenage shooters killed 12 classmates and a teacher before killing themselves in 1999.
The shooting also came a day before the first anniversary of the school massacre in Newtown, where a gunman killed 20 children and six adults at Sandy Hook Elementary School.
Tracy Monroe, who had step-siblings who attended Columbine, was standing outside the high school looking at her phone, reading text messages from her 15-year-old daughter inside.
Monroe said she got the first text from her daughter, sophomore Jade Stanton, at 12:41 p.m. The text read, “there’s sirens. It’s real. I love you”
A few minutes later, Jade texted “shots were fired in our school.” Monroe rushed to the school and was relieved when Jade texted that a police officer entered her classroom and that she was safe.
Monroe was family friends with a teacher killed in the Columbine shooting, Dave Sanders.
“We didn’t think it could happen in Colorado then, either,” Monroe said.
Police were outside the school, and students were seen walking toward the school’s running track with their hands in the air. Television footage showed students being patted down.
More than 2,100 students attend Arapahoe High School where nine out of 10 graduates go on to college, according to the Littleton Public Schools website.