The high-achieving senior who shot female student, 15, and killed himself after taking Molotov cocktails and shotgun to school

The shooter: Karl Pierson, a senior at Arapahoe High School, has been named as the shooter who killed himself and injured three others

The high school senior student who walked into his Colorado high school with a shotgun and two explosives was targeting the librarian and was upset over the fact that he had been benched from the debate team earlier this week. 

Karl Pierson has been identified as the shooter who went into Arapahoe High School at around 12.30pm Friday afternoon asking for the librarian by name. Reports say that he did not conceal his shotgun and word traveled to librarian Tracy Murphy- who doubled as the speech and debate team advisor- that he was the target. 

Police responded to the scene and found Pierson, 18, had injured three other students and shot at the librarian but missed, before killing himself with a self-inflicted gunshot wound. 

A fellow student told local news station KDVR that he was coming back to school after running an errand during his lunch break and was in the parking lot when he saw the librarian running out of the building. 

‘He seemed incredibly shocked, he was in awe,’ student Frank Warnoff said of Mr Murphy. 

Warnoff said that Murphy kept telling him what happened inside, naming Pierson and saying what appears to be the motive for the shooting. 

‘I docked him from the speech and debate team and that just shocked him,’ Warnoff recalled Murphy telling him. 

‘(Mr Murphy) just kept repeating (the shooter’s) name and what happened and where (the shooter) was.

Debate team: Karl Pierson (left) was a member of the debate team and previously competed at nationals for the school, but his coach, librarian Tracy Murphy (right) allegedly demoted him earlier this week causing him to snap

Sheriff Grayson Robinson said at an afternoon press conference that the shooter was a current student at the school but other reports suggested that he may have recently been suspended.   

The police have not publicly released Pierson's name, but public records and local news reports, as well as debate team and cross country team listings all point to Pierson as the shooter.

SOURCE-DAILYMAIL