The student who killed one and injured three in a mass school shooting was obsessed with guns and violent TV shows such as 'Breaking Bad'.
Caleb Sharpe brought a rifle and a handgun in a duffel bag into his high school in Spokane, Washington, before opening fire outside a classroom.
Police said the first weapon jammed, prompting a fellow student to bravely intervene.
But the heroic boy, named locally as Sam Strahan, was shot in the head and died.
Sharpe then turned and fired into the hallway, hitting three girls.
They are in hospital but are expected to survive.
A member of staff apprehended Sharpe at Freeman high school before he could do any more harm, and he is now in custody.