WASECA, Minn. (AP) — A teenager who told authorities he was planning a massacre at a Minnesota school has been sentenced to up to 10 years of probation, which will begin with treatment at a secure facility.

Eighteen-year-old John LaDue was sentenced in Waseca County District Court Monday on one count of possessing an explosive device. LaDue earlier pleaded guilty to the charge and five other similar counts were dropped.

The Star Tribune reports LaDue will serve five to 10 years of probation, including an unspecified amount of time at the secure treatment facility for autism spectrum disorder patients. He will eventually move to a halfway house and then supervision.

LaDue was 17 when authorities say he plotted an attack at Waseca Junior-Senior High School. He was initially was charged as a juvenile with attempted murder and eight other counts.