A suburban Denver student shot two other students at a high school Friday before he apparently killed himself, authorities said.
Arapahoe County Sheriff Grayson Robinson said the shooter entered Arapahoe High School in Centennial armed with a shotgun and looking for a teacher he identified by name.
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The teacher immediately left the school when he learned the student was looking for him, Robinson said.
The shooter then shot two students, one of whom is in serious condition at a hospital. The other is also hospitalized, with a minor gunshot wound. It was initially believed the student in serious condition confronted the shooter, but Robinson now says that wasn't clear.
Robinson said the student is believed to have acted alone. 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 Carpenter.
"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.