It's the perfect storm. Big forklift not normally used in a warehouse, he accelerates by mistake in reverse, doesn't brake so we have impact and a ramming impact, hits the weakest point in the warehouse the frame holding up the tunnel aisle. Because he is ramming the rack he takes out at least two frames causing the rack above to buckle at mid point. This causes the top part to bend out onto the rack opposite. The opposite rack beams become overloaded and are being dragged out and forward so they in turn buckle their frames. This causes both sides of the aisle to collapse into the aisle. This whole thing is ultra unusual. Rack normally peels from an end bay with the bottom of the frame giving way.The frame then leans in to the aisle and peels away from the back to back rack bringing with it several bays. But that is usually it, none of this dramatics.
It's almost as this was a movie. "Shaken not stirred" " Drink responsibly"