A natural gas explosion called suspicious in origin by firefighters destroyed an unoccupied house Friday morning.

The explosion blew out walls and ceilings of the Paul and Marlo Evans home, 385 E. 100 South, about 9:30 a.m., said Spanish Fork Fire Chief Errol Smith. Damage to the home, which was being remodeled, was estimated at $40,000."It was serious enough to make the home absolutely unlivable," Smith said of the explosion. Several small fires dotted the wreckage.

Spanish Fork Police Chief Dee Rosenbaum said some items from the home - personal items and natural gas connectors - have been sent to the state crime lab for analysis. "Natural gas happened to leak into the home. We don't know the source of that leak."

Rosenbaum said investigators are still trying to determine how the gas was ignited. The couple and their child were out of state when the explosion occurred.