A fire marshal told relatives of the home's owners that propane gas appears to have ignited, setting off the 4 a.m. blast., the Ellwood City Ledger reported. Emergency workers also reported hearing ammunition popping as it exploded.
The house in South Beaver Township was owned by Ray Trautvetter, 74, a retired steel worker, and his wife, Janet, 69. Janet Trautvetter ran her own business, Janet's Catering, out of the house.
Peter Sergi, who lives nearby, said he was awakened by the explosion. By the time he got to the house, it was in flames.
The explosion was so powerful that debris was carried as much as a quarter mile.
South Beaver is a small town on the Ohio border.