On Saturday Jan 9th at 9:00 am we received a call for a working truck fire in a residental area. A LT responded from home and upon arrival found a engine compartment fully involved. A minute later small popping noises were heard from the rear of the bed. He asked the driver what was back there and he said only tools. After multiple explosions were heard the driver finally said that a nail gun with 22 loads was in the front seat. The first engine and rescue kept back due to concern for safety and we attacked the fire with a deck gun then finished with a line only from the front with a minimum amount of members. This incident had all of the making of a serious one if we were too close went the rounds went off. I am interested in hearing any other reports of similar incidents involving nail guns or items in vehicle fires.