Arapahoe student: Shooter "wasn't some creepy loner kid"

New cell phone footage obtained by "CBS This Morning" shows the scene inside Arapahoe High School
New cell phone footage obtained by "CBS This ... 02:37

Arapahoe High School in Centennial, Colo. is closed Monday. Investigators are still trying to learn why a student shot a classmate in the head and then killed himself.  It happened Friday, not far from Columbine High School in Littleton, the site of the 1999 shootings.

New cell phone video obtained by “CBS This Morning” shows the scene after the shooting as Arapahoe students were being evacuated to safety. The rampage lasted just 80 seconds. Shotgun in hand, 18-year-old Karl Pierson went to the school library around 12:30 p.m. Friday afternoon, looking for his debate teacher, Tracy Murphy.

“We believe based on the fact that he was armed with multiple rounds, armed with a machete and three incendiary devices, his intent was evil, and his evil intent was to harm multiple individuals,” said Grayson Robinson, Arapahoe County Sheriff.

Pierson was apparently still upset with Murphy for disciplining him back in September.  Murphy escaped to the library, but 17-year-old Claire Davis, who was in a nearby hallway, was not so lucky

“She was shot point blank with a shotgun in the face,” said Colorado Governor John Hickenlooper on “Face the Nation.” “I visited her and her family. She's obviously in a coma.”

Senior August Clary was taking a chemistry quiz when the gunshots rang out. His teacher locked down the classroom.

“We were hoping to God that we weren't going to die,” said Clary. “But, everybody was staying quiet and if you were crying, you were crying as quietly as you could.”

With officers closing in, Pierson set off a Molotov cocktail, before taking his own life in the back of the library.  Swat teams then went room to room and in a scene reminiscent of Columbine, students fled the school with their arms up in the air to show they were unarmed.

Clary, who has known the suspect since third grade, said Pierson was an eagle scout and a smart student with a passion for politics, who hated losing an argument.

“He wasn't some creepy loner kid,” said Clary. “He had a lot of friends.”