An employee was operating a forklift to pull a load of wood pulp from a three-high stow in a warehouse. He grabbed a load from the stack with the clamp and was backing out when the load pulled an adjacent bundle, causing it to become unstable. The adjacent bundle fell against the forklift mast, causing the forklift to tip over. The employee suffered a left forearm laceration and a crushed left leg above the ankle, which required amputation.