Abstract: At 12:30 p.m. on July 23, 2021, two employees were working at a shipbuilding and maintenance site operated by NASSCO in San Diego, California. Employee #1 was operating a crane to rig and position a 700-800-pound steel vent hood and also operated a scissor lift to bring Employee #2, a welder, to approximately 20 feet to tack weld the vent hood to the ship body. While the vent hood was suspended, Employee #1 pushed it and performed limited tack welding. The jib of the crane shifted, causing the vent hood to break free and strike the scissor lift, which then tipped over. Both employees fell with the scissor lift. Employee #1 sustained fractures to the hand, back, and other injuries, and Employee #2 sustained a crushing injury to the left leg, which later required below-the-knee amputation. Both employees were transported via ambulance to UCSD Medical Center for admission and treatment.