Abstract: Employee #1 and #2 and a coworker were hired by the owner of a mobile home park to fix a leak in an underground water line. They dug up the area and repaired the leak. In close quarters in the hole were a gas line and several electrical lines. The employees smelled natural gas as they worked. One employee became dizzy from the smell. The employees were asked to repair the gas leak. There was water in the trench from the water line so they were using a submersible pump to remove it. They tested the gas line with soap, found the leak, and started the repair. The coworker was overcome by gas vapors and was lying down outside the trench. Employee #1 cut into the gas line with an electric reciprocal saw. He had cut about halfway when the gas ignited and blew up, knocking him completely out of the trench. He was rolling on the ground 20 ft away on fire. He was finally caught and taken under a shower at a nearby mobile home to put out the flames. Employee #2, who was standing just outside the trench, received burns on his left arm, face, and chest. The coworker, who was lying down, was not hit by the explosion and fire. The injured employees were quickly evacuated to the UC Burn Unit. Employee #1 received severe burns to 65 percent of his body and was hospitalized for 23 days. Employee #2 was treated and released the same day.