The student who shot a fellow student in the hallways of Arapahoe High School in Centennial, Colo., was no longer an active participant on the debate team, and The Denver Post reports that may be among the motives behind the attack. Karl Pierson, an 18-year-old senior, walked into the school Friday with a shotgun, ammunition, a machete, and Molotov cocktails. He fired a shotgun blast at student Clare Davis, set a fire in the school library, then shot himself to death. Clare Davis, 17, was wounded and was in a coma in critical condition, officials say. A friend of Pierson says the student had an ongoing feud with Arapahoe's debate coach, Tracy Murphy, and had threatened to kill him.
MORE: Arapahoe High has cancelled classes this week and will not reopen until after the winter break. (The Denver Post)
ALSO: The response by school and law enforcement officials to the shooting at Arapahoe High School show how security procedures have improved since the 1999 shooting at nearby Columbine High School.