JACKSON, Wyo. (AP) — Fire investigators say they don't know what caused a leak at a propane business in a Wyoming resort town to ignite in a series of dramatic explosions.

Thursday's explosions and fire in Jackson destroyed the AmeriGas store, a fitness center and at least a dozen cars. Nobody was killed and only a few minor injuries happened as people rushed away.

The gas leaked from a truck that had arrived to fill underground propane tanks.

Fire Marshal Kathy Clay says investigators continue to look into what caused the leaking propane to ignite.

Firefighters prevented the truck's propane tank and an underground propane tank from exploding. The truck was carrying about 1,000 gallons of propane and the underground tank some 15,000 gallons.