Putnam, CT- PUTNAM — The cause of natural gas explosion that leveled one house, seriously damaged two others, and destroyed two cars remains under investigation.

Putnam Fire Marshal Normand L. Perron said the owners were not home at the time of the explosion at 10:30 a.m. Friday. Workers in the house at 53 Fremont St. detected a problem and called the gas company. The explosion occurred just after a Yankee Gas company employee checked a meter and led workers from the house, which had been bought two weeks earlier by Nathaniel and Elizabeth Gould.

Fire from the explosion damaged houses at 49 and 57 Freemont St. and also singed the vinyl siding on a nearby house on Chapman Street.

The investigation is being conducted by Fire Marshal Perron, the state fire marshal’s office and Putnam police. Firefighters from about 10 departments responded. No injuries were reported. Fire Chief Norman A. Bernier said an unidentified gas company employee was later taken to a hospital as a precaution, where he was treated and released.