Classes at Arapahoe High School are not expected to resume until after the holidays. This comes as 911 tapes from Friday's shooting have been released.
In one recording, a caller is heard describing the condition of a victim.
"I have a student down in the athletic hall, she's bleeding bad," the caller said.
The suspected gunman, 18-year-old Karl Pierson, went to the campus on Friday with a shotgun he legally bought a week before, ammunition he bought that morning, a machete and several Molotov cocktails.
Police say Pierson's intended target was his debate coach and librarian, Tracy Murphy. The coach had disciplined Pierson in September for unclear reasons.
After that, Pierson allegedly threatened to kill Murphy. Friends thought it was a joke, but when Murphy reported the threat to the school, Pierson was suspended.
When Pierson apparently went looking for Murphy on Friday, he instead shot 17-year-old Claire Davis in the head. Davis is in a coma in critical condition. It appears she was a random victim.
Pierson did ignite a Molotov cocktail inside the school before killing himself as the campus deputy sheriff closed in. The entire ordeal lasted 80 seconds.
Those who knew Pierson are speaking out.
"He's not a monster. He's one of the best people I knew. He's not this killer. He's Karl Pierson, he's one of the best people I know," said Pierson's prom date.
Authorities say it's unclear how the shooting could have been prevented. Pierson didn't exhibit any warning signs of mental illness, and the gun laws in Colorado target assault weapons more than shotguns, which are widely used for hunting.