PORTLAND, Ore. - An Oregon teenager intended to blow up his school in a plot "forged and inspired by the model of the Columbine shootings" and he will be charged with attempted aggravated murder, a prosecutor said late Saturday.

Grant Acord, 17, will be charged as an adult and also faces six counts of manufacturing and possessing a destructive device after investigators found six bombs in a secret compartment in his bedroom, Benton County District Attorney John Haroldson said.

Acord was taken to a juvenile jail Thursday night after police received a tip that he was making a bomb to blow up West Albany High School, about 75 miles south of Portland.

Haroldson said Acord had written plans, a checklist, and a timeline for an attack. Investigators found pipe bombs, Molotov cocktails, a Drano bomb. and a napalm bomb, Haroldson said.

Police found no bombs at the high school.

Haroldson declined to provide the date Acord allegedly planned to attack the school, but said it would be included in court paperwork to be filed after the Memorial Day weekend.

"That said, there were also some indications that it could happen at any time, too," Haroldson said. "So you have A - the methodical planning, then B - I suppose he could get really excited about it and go early."

Haroldson said he was not aware whether Acord had any major problems at school. "In any case that you have a young person that in essence plans to take a video game approach to killing people . . . you have to take a close look at the mental-health issues," he said. "And the process will certainly provide for that."