A suspicious fire destroyed a huge generator and a 1,500-gallon tanker truck at the Richard Rogers sand and gravel yard south of Green Valley, St. George police said.

The fire, which Rogers said he discovered at noon on Tuesday, ignited 150 gallons of diesel fuel inside the tanker truck and destroyed a $6,000 welder and other tools inside a nearby moving van, he said.Authorities from the Utah State fire marshal's office were expected to investigate the fire, believed to have been arson-caused sometime between Sunday night and Monday morning, Police Det. Bill Sevy said.

Damage was estimated at $125,000.

Rogers said he is offering a substantial reward for information leading to the arrest and conviction of those involved.