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Colorado school shooter entered through open door

One student was injured in a shooting at Arapahoe High School in Centennial, Colo. on Friday, Dec. 13, 2013. The gunman, a fellow student, was found dead inside the school of an apparent self-inflicted gunshot wound.

December 30, 2013 12:00:00 AM PST
Authorities in Colorado say the suspect in the deadly high school shooting earlier this month entered the school through a door that was supposed to be locked. But that door was usually propped open because it was more convenient for people to walk in and out of campus.

Karl Pierson, 18, went on the shooting rampage on Dec. 13 at Arapahoe County High School in the southern suburb of Centennial.

He shot and killed himself as sheriff's Deputy James Englert, who is assigned as a resource officer at the school, closed in on him.

According to investigators, Pierson was carrying a shotgun, more than 125 shotgun shells, a machete and three homemade firebombs.

Claire Davis, a 17-year-old senior, was shot in the face. She died a week later from her injuries. Authorities have said Davis was a random victim and that Pierson's main target was a speech team coach who had disciplined him.

The Associated Press contributed to this report.