VADNAIS HEIGHTS, Minn. (AP) — Prosecutors on Monday charged a Minnesota man with illegally possessing a machine gun and a short-barreled shotgun after his 13-year-old son allegedly threatened a classmate.

Authorities said they discovered a cache of weapons during a search of the family's home that was prompted by the boy's alleged threat last week. The family lives in Vadnais Heights, a suburb of St. Paul.

The father was charged with two felony weapons counts and a gross misdemeanor for negligently storing loaded firearms where a child could get at them. He remained in jail with bail set at $25,000 after making his first appearance in Ramsey County court on Monday.

The son is accused in juvenile court of making threats. His first court appearance, which is not open to the public, also was scheduled Monday.

Calls by The Associated Press to a phone number listed for the family's home rang unanswered Monday, and court documents don't yet list an attorney for the father. The AP isn't naming the father to protect the identity of the teen, whose name isn't being released because of his age.

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.

According to the criminal complaint against the father, his son was home alone when law officers executed a search warrant at the home. The father arrived and told an investigator there were guns in the home and that the guns were his. Authorities seized numerous guns and ammunition, including two possible explosive devices.

The boy's mother also was arrested, but prosecutors returned her case to the sheriff's office for possible gross misdemeanor charges by the Vadnais Heights city attorney.

Ramsey County Sheriff Jack Serier said a "potential tragedy was averted." But Vadnais Heights Mayor Bob Fletcher, the country's former sheriff, was among those critical of how the Serier's office handled comments by the 13-year-old boy, who has autism.

Fletcher said the City Council thought there was a terrorist cell in the city "based on the hype created by the sheriff's department."

The boy's grandfather told the St. Paul Pioneer Press that his grandson said he would "shoot up" the school when he was talking with classmate, but that he had no intention of carrying it out.