An Oregon teenager accused of building bombs and plotting an attack on his high school in Albany has admitted to the charges in juvenile court.

Seventeen-year-old Grant Acord appeared before a judge in Corvallis on Monday. He admitted to six counts of manufacture of a destructive device and two counts of unlawful use of a weapon.

A judge sent Acord to the Oregon Youth Authority, which can hold him until his 25th birthday.

In a deal with prosecutors, adult charges of attempted aggravated murder were dropped.

Police arrested the teen last year, saying he wrote detailed plans to "shoot and throw bombs throughout the school," and then kill himself.

Authorities discovered two pipe bombs, two Molotov cocktails and at least two Drano bombs hidden beneath the floorboards in Acord's bedroom.