Note: the following is an update to Thursday’s fire that claimed one life and sent two others to the hospital. This release was issued by East Pierce Fiire and Rescue.

The Pierce County Fire Marshal’s Office has established that the fatal mobile home fire in Prairie Ridge yesterday started on the outside deck in front of the home. According to Fire Marshal Dave Dupille, the cause of the fire will remain undetermined, although investigators were able to rule out arson.

Witnesses reported hearing explosions coming from the home during the fire. Dupille says that the sounds of explosions are characteristic of a rapid high heat in a typical house fire, but it was not the cause of the fire. He says that none of the propane tanks found in the front of the property had burst. Only one, small tank that was found in the backyard had split.

Firefighters from East Pierce Fire and Rescue were called to the scene on the 14700 block of Prairie Ridge Drive East at 3:57 p.m. Thursday. They arrived less than four minutes later to find the doublewide mobile home fully involved. Two people had been able to get out of the house on their own. They reported that one person was still trapped inside.

Firefighters entered the burning structure and brought one victim from the home. That person was pronounced dead at the scene. The other two occupants were transported to Harborview Medical Center in Seattle with life-threatening injuries.

Dupille says that the most likely cause of the explosions the neighbors heard was either pressurized containers—such as aerosol cans—heating until they explode or the sound a backdraft makes when a fire has consumed all the available oxygen and suddenly explodes when more oxygen is made available, typically because a door or window has been opened. “There was some ammunition found at the scene.

“That may have contributed to [the sound of explosions] as well,” he says.

The loss of the home and contents is estimated at $45,000 to $50,000.