ALPINE - A propane-tank explosion ignited by the spark of a lighter inside an East County trailer home severely burned a 60-year-old man, authorities said today.

The victim, known only as Fairweather, was taken to UCSD Medical Center, where he was listed in guarded condition with first-degree burns to his face, and second- and third-degree burns to his arms, chest and legs, according to the San Diego County Sheriff's Department.

The accidental explosion occurred shortly before 7:30 last night in the 15000 block of Old Highway 80 in Alpine when the victim lit his lighter inside his trailer, said Sgt. Conrad Grayson of the sheriff's Bomb/Arson Unit.

Investigators determined the lighter's spark set off fumes that had been building from a leaking 5-gallon propane tank attached to a heater in the trailer, he said.