(USA TODAY) A librarian and debate team coach is believed to have been the gunman's intended target in a shooting at a Colorado high school.
According to KUSA-TV in Denver, Tracy Murphy implemented "active-shooter protocols" after he learned 18-year-old Karl Pierson — whom officials have identified as the shooter — was armed with a shotgun and asking for Murphy at Arapahoe High School on Friday. Murphy then left the scene, a move Arapahoe County Sheriff Grayson Robinson said may have helped to limit the potential carnage.
On Friday night, Robinson would not elaborate on any possible motive except to say Pierson, who was found dead of a self-inflicted gunshot wound, had had a "confrontation or disagreement" with the teacher.
An Arapahoe County deputy escorted Murphy home to pick up a few belongings on Friday night. Murphy declined to talk about the shooting. What he has to say about his interactions with Pierson likely will be a key part of the investigation.
A 15-year-old girl suffered a gunshot wound and remained in critical condition as of Friday evening. Two other students suffered minor injuries.
On Saturday, students were able to return to the high school for the first time since being evacuated during the shooting Friday afternoon. They picked up their cars, but they were not allowed to go inside the school, which remains a crime scene.
It is unknown when students will be allowed back into the school to pick up their backpacks, cellphones or other items left behind. Classes are canceled on Monday. Finals were scheduled to start Tuesday, but those also have been canceled.
"Communication about final exams will come as we have more information, but they will not occur in any format until after the holiday break," according to a letter from the Arapahoe High School Administrative Team.
The shooting — on the eve of the first anniversary of the Newtown school massacre, in which 20 students and six staffers were killed — sent scores of terrified students and staffers at Centennial's Arapahoe High School scurrying at about 12:30 p.m. Police and other first responders quickly mobilized to surround the 2,220-student school.
The gunman also brought two Molotov cocktails inside the school and exploded one, KUSA-TV reported. The other was found and removed by the bomb squad.
The incident unfolded when the armed student entered the west side of the school from a student parking lot. He told other students he was interested in confronting a specific teacher.
Many students locked themselves in classrooms until first responders arrived. Some said they heard several gunshots in a hallway near the school library.
"We were shaking, we were crying, we were freaking out,'' 9th grader Whitney Riley told CNN.
Jessica Girard was in math class when she said she heard three shots.
"Then there was a bunch of yelling, and then I think one of the people who had been shot was yelling in the hallway, 'Make it stop,' " she said.
Contributing: KUSA-TV, Denver; Associated Press