Abstract: On November 3, 2003, Employees #1 and #2 were installing roof trusses on a 3,380 sq ft single family two-level with a basement. Both employees were settings trusses and were in place awaiting the crane operator to swing a truss assembly gable, plywood covered truss that was lifted approximately 50 ft. The crane lifted the truss over gable already set and while the crane operator lowered the gable truss, it snapped and swung, striking the trusses already set and creating a domino affect resulting in both employees to be knocked off the areas that they were operating from. Employee #1 was knocked off from a 24 ft ladder and Employee #2 from the west wall and truss he was perched on causing employees to fall approximately 30 to 40 ft. Employees were taken to Maryland Shock Trauma Unit by Police helicopter unit, each employee suffer multiple injuries. Employee #1 was hospitalized while Employee #2 was not.