An American teenager who planned to blow up his school will be charged with attempted murder after six bombs were found in a bedroom.

Grant Acord, 17, planned to attack his school in Oregon in a plot "forged and inspired" by the Columbine High School massacre, according to police. Twelve pupils and a teacher died in the 1999 attack, when two students opened fire on their school before committing suicide.

Acord was arrested at his home in North Albany on Thursday night after police received a tip-off that he was planning to bomb West Albany High School.

John Haroldson, the district attorney, said the teenager had written plans, a checklist and a specific timeline for the attack. Investigators found pipe bombs, Molotov cocktails, a Drano bomb and a napalm bomb, Mr Haroldson said.

The teenager had created a secret compartment in the floorboards of a bedroom in another family member's house nearby, in which he hid the bombs. "His goal was to model the Columbine shootings with some adjustments that would make it a greater success," said Mr Haroldson.

Susie Orsborn, the head teacher, sent a note to parents asking them to encourage their children to speak to the police if they had any information about the plot.

Acord will appear in court on Tuesday.

Telegraph, London