EPHRATA — Fire destroyed a storage shed Saturday about a half-mile north of Ephrata, torched more than 500 acres and threatened about 30 homes, fire officials said.

Extreme heat, with temperatures reaching 106 degrees, along with rough terrain made fighting the fire difficult, Chief Shane Heston of Grant County Fire District 13 said Monday.

Several firefighting vehicles were damaged, including a snapped axle on one truck. Radiators and a transmission were damaged on other vehicles. A couple of truck tires were blown out.

"There were boulders the size of dishwashers out there," Heston said.

A crop-duster aircraft dropped water, helping extinguish the blaze.

No injuries were reported and no homes were burned, the chief said.

It began about 1:50 p.m. at Road 17.5 N.W., just off Highway 28, Heston said. The fire was wrestled under control about 8:30 p.m., he added.

A few older cars, a travel trailer and at least two unused outbuildings were burned along with brush and landscaping, he said.

Forty-foot-tall flames jumped from juniper trees at the scene, he said.

The storage shed, where the fire may have started, contained ammunition, leading to explosions, the chief said.

District 13 was assisted by the Ephrata and Soap Lake fire departments. Grant County Fire Districts 7 and 3 also assisted. About 50 firefighters battled the blaze.

The Grant County Fire Marshal's Office is investigating.

There is currently no indication what started the fire, an official in the fire marshal's office said Monday.