A man who stashed a cache of illegal weapons at a Bellevue storage facility was sentenced Friday to four years in prison and three years of supervised release after being convicted of five felony charges.

Ronald L. Struve, 67, of Spokane pleaded guilty in March to charges related to possession of plastic explosives and unregistered firearms. His arsenal included 37 machine guns, 54 high-explosive grenades, two grenade launchers, and eight silencers, according to records filed in the case.

U.S. District Judge Marsh Pechman ordered Struve to undergo mental-health treatment, and said his weapons stockpile represented a “huge danger to the community.”

“The possibilities are frightening what could have happened with a fire or earthquake or break-in,” she said.

Struve rented a storage unit in Bellevue under a false name, but the locker went up for auction after he failed to pay the rent.

The buyer notified the Bureau of Alcohol, Tobacco, Firearms & Explosives after discovering weapons in one of the boxes.

Agents tracked Struve to Spokane and located a second storage locker with eight more machine guns and another unregistered firearm. Many of the weapons had been stolen from the military, according to records filed in the case.