Abstract: At approximately 1:00 a.m. on November 22, 1999, employees working on the propane bottling fill line of a metal fabricating company noticed a ruptured hose leaking on one of the two propane bottling fill machines. One of the employees paged maintenance to report the leak; however, he got no response. He attempted a second page and an employee from maintenance reported to the fill room area. The propane bottling fill line was shut down and Employee #1 (the maintenance worker) and Employee #2 (a lead assembly worker) entered into the fill room to shut off the propane line to the fill machine. Employee #1 accessed the shut off valve using a stepladder that was in the fill room. Employee #2 opened two doors to the outside of the building to let fresh air into the room. Employee #1 then left the fill room to start up the second fill machine to keep production going while he attempted to make repairs of the ruptured propane fill line on the propane bottling fill machine. He then went back into the room along with Employee #2. While inspecting the propane boost pump, Employee #1 reported he saw what he believed to be a blue flame adjacent to the boost pump. The next thing Employee #1 recalled was an explosion with fire. The explosion and fire consumed the propane bottling fill room, the rework area (adjacent to the fill room), the assembly line corridor, and the final bath area where it ignited approximately 47 propane cylinders that were set aside because they leaked. Employee #1 (the maintenance worker), and two assembly workers (Employees #2 and #3) all sustained first-, second-, and third-degree burns to their faces arms and chests. All three employees were transported to hospital and admitted for treatment. One other worker was injured, but no treatment was required.