MINNEAPOLIS (AP) — Authorities say a 13-year-old boy and two adults have been arrested after a cache of firearms, ammunition and explosive devices and at least one ballistic vest was discovered at a Vadnais Heights home.

The Ramsey County Sheriff’s Office says Friday’s search by federal and local officers was spurred by a parent’s report that a student from the Academy for Sciences & Agriculture in Vadnais Heights made a threat against another student.

Ramsey County Sheriff Jack Serier says the arrests averaged “a potential tragedy.”