Abstract: Employees #1 through #5 were trying to solve a problem with a piece of machinery that was stationed in a pit. It appears that Employee #5 either entered the pit to check the pump or fell in while checking the equipment. Employees #1 through #4 entered the pit to rescue Employee #5. Employee #4 was the last one to enter the pit at this time. When Employees #6 and #7 arrived at the scene, Employee #6 took a rope, entered the pit, and attempted to place the rope around Employee #4. Feeling overcome by inhalation of toxic gases, Employee #6 exited the pit, then passed out when he reached the top. His breathing had apparently stopped. Employee #7 revived Employee #6 with mouth-to-mouth resuscitation. Employee #7 then entered the pit, but found it difficult to breathe so he exited immediately. Others arrived at the scene. Employees #8 and #9 entered the pit and retrieved the bodies. Employee #4 was still breathing and a positive pressure respirator was applied until an ambulance arrived. Employee #4 was then treated by the paramedics and transported to the hospital. Employees #1 through #5 died. Employees #6, #7, #8, and #9 did not seek medical treatment.