Abstract: Employee #1 was part of a roofing crew that was removing and replacing an old roof covering. Along with the roof covering, five 37 1/2 in. square ventilator frames had been taken out. There were wooden trap doors under the ventilators that opened into the building. While cutting 2 by 4 wood supports and plywood to cover the openings, Employee #1 fell through one of the trap doors and dropped 18 ft 6 in. to the floor inside the building. Paramedics from the El Segundo City Fire Department transported Employee #1 to the UCLA Medical Center, where he was hospitalized with head, shoulder, and ankle injuries.