Abstract: Employees #1, #2, and #3 were working on a new building which was being added to an apartment complex. Employee #1 went into the basement level utility room to solder a connection to the water supply. When he lit the torch, an explosion occurred. The flame front went throughout the basement room and passed through a room one level above and out the exterior door. Employee #2 was in the upper room and Employee #3 was outside the exterior doorway. Employee #2 received second- and third-degree burns to his legs, arms, and body and Employee #3 received singed hair and minor burns. Employee #1 was lying on the floor of the basement. He stated that it got too hot and he ran to the ladder and climbed out through the flames and sustained burns to arms and head. The fire was then extinguished within seconds. Employees #1 and #3 were not hospitalized and Employee #2 was hospitalized with his injuries. An investigation by the fire department in conjunction with the LP gas supplier determined that a leak had developed in the supply pipe to the occupied building next to the building under construction. It was believed that the gas flowed along the drainage gravel between the buildings and entered the lower level of the utility space. The utility space had no exterior doors or windows for ventilation and met the definition of a confined space. Entry to the area was accomplished by climbing down a job-built ladder.