Firefighters responded to the home at 11:29 p.m. for a report of a structure fire with explosions, Croydon Fire Chief Steve Rizza said.
The explosions turned out to be 20-pound propane tanks just outside the home, as well as ammunition stored inside the home, Rizza said.
The fire wasn't under control until 3 a.m., and firefighters were on the scene putting out hot spots until 6 a.m.
"The reason is the metal roof," Rizza said. "It really acts like an oven."
After investigating the scene with a state fire marshal, Rizza said late Thursday morning that the fire appears to have been accidental and caused by a woodstove.
The home had structural, fire and water damage.
The homeowners were not home when the fire occurred, and no firefighters were injured fighting the blaze, Rizza said.