Firefighters battling a fire at a two-story storage building in Garden City heard noises that sounded like small arms ammunition exploding.
Boise Fire Department spokeswoman Lynn Hightower says the fire reported just before 5:30 p.m. Sunday threatened a nearby charter school.
Hightower says one firefighter was hurt after being shocked by a downed power line, but officials described the injury as minor. No one was injured by the small explosions.
Boise Fire Battalion Chief Aaron Hummel says a man was in the building when the fire started, but made it out safely. He and two others were treated at the scene for smoke inhalation.
The cause of the fire is still under investigation.