An employee drove a truck with a roll-off container into the yard. They got out of the truck and released the safety chain on the roll-off container in order to unload it, but ammunition containers located inside the roll-off container had shifted during transit. When the employee undid the safety chain, a pallet of ammunition containers fell out of the roll-off container and crushed the employee, resulting in several broken ribs, a broken arm and clavicle, and a punctured lung.