Abstract: At 8:15 a.m. on March 15, 2015, an employee was working on a battery to a circulating pump that was located at a oil rig site. The tool being used was a standard wrench. Based on initial interviews, the employee was working on the battery to a circulating pump. The battery was approximately 20 feet away from six frac tanks. These tanks contained oil, water, and hydrocarbons that were floating on the water. The employees stated they saw gas vapors come from the hatch of one of the frac tanks and a short time later, a flash fire started from behind the tanks. Two employees were burned from the flash fire. Employee #1 received burns to his hands and elbows. Employee #2 received burns to his back, arms, face, hands, and back of knee. One employee was killed. However, the report did not specify which employee was killed.