The student at West Albany High School allegedly hid at least six bombs and bomb-making material in a secret compartment under the floor of his bedroom, Benton County District Attorney John Haroldson said.
Grant Acord, 17, was arrested late Thursday at his home on two counts of possession of a destructive device and two counts of manufacture of a destructive device, according to the Albany Police Department.
But Haroldson said today that Acord will be charged with aggravated murder in adult court. He is expected to be arraigned Tuesday in Benton County Circuit Court, the prosecutor said.
"The charge of attempted aggravated murder requires that we prove that a substantial step was taken toward the completion of the crime," he said. "In this case, we would be relying upon evidence of plan. Diagrams, checklists, a plan to use explosive devices and firearms to carry out a plan specifically modeled after the Columbine shootings."
According to Haroldson, the explosives police allegedly found included pipe bombs, Molotov cocktails, napalm bombs and explosives made from drain cleaner.
The school was allegedly chosen because it was a "target-rich environment," the district attorney said.
Another ABC News article reports that Acord spoke to classmates about bombs and the different materials needed to manufacture them, just weeks before he planned to carry it out.
Via the West Albany High School website, the school has one uniformed resource officer, although after Acord's arrest, reports state that there will be an increased police presence at that school as well as Memorial Middle and Liberty Elementary, which share a common property.