Employees were removing sections of side panels from an open ended cooler that was approximately eight feet above the lower surface. As employees carried a disconnected side panel across an unbolted belly panel, the belly panel collapsed. The employees fell through the opening and the side panel they had been carrying fell with them. Employee 1 suffered a fractured left tibia and fibula and a fractured right femur. Employee 2 suffered a fractured left ankle, a dislocated left patella, and a back injury. Both employees were hospitalized.