A pre-dawn explosion that flattened a west-side Billings, Mont., home, killing one man and injuring a youngster, apparently was caused by an exploding propane tank, officials said Tuesday.

The 4:13 a.m. blast killed Kim H. Sutton, 34, the owner and manager of a defunct appliance repair store, authorities said. His son, Travis Sutton, 12, suffered second- and third-degree burns over 24 percent of his body and was flown to the University of Utah's Intermountain Burn Unit in Salt Lake City.The boy was in critical but stable condition Wednesday, according to a nursing supervisor at the hospital.

They were the only occupants of the house and the only known injuries from the blast, said Fire Chief Dick Blee.

A preliminary investigation indicates that a smoldering fire in the house basement touched off a 5-gallon propane tank that was improperly stored, he said.

Several cylinders of freon gas also were stored in the basement, he said.

"It was a blast like we haven't experienced in Billings," Blee said. "I've been with the department 24 years and have never seen anything like this one."

The Sutton home was destroyed, houses on either side of it and across the street were set on fire, and about eight nearby homes were severely damaged. Those fires were extinguished by dawn, the fire chief said.

Police cordoned off the neighborhood and people were evacuated for several hours from nearby homes. Blee said the residents were allowed to return after officials determined no danger of further explosions remained.

However, residents from three severely damaged houses did not return home and were believed to be staying with friends.

Windows were shattered in businesses along 24th Street West, a major business artery a few blocks from the explosion.

Blee said the blast awakened people eight to 10 miles away, his own family included.

"We had calls from people in a lot of different parts of the city," he said. "I live seven or eight miles away and it woke us up."