Abstract: A natural gas well was being worked over to plug the existing producing zone in order to perforate a better producing zone. The well was on a vacuum throughout the procedure. A lost circulation pill was spotted in an attempt to plug the old perforations and establish circulation. When circulation was achieved with well fluids at the surface, a gas bubble came up with the fluid. The gas bubble ignited and exploded, killing Employee #1 and injuring four other crew members. Employee #2 and #3 were hospitalized, and Employees #4 and #5 were treated for burns to their arms and released. The well is under control with zero surface pressure and is awaiting the arrival of another workover rig. The original workover rig was destroyed in the fire.