When you come upon a vehicle that is positioned upright on its wheels, you should:

Chocking the wheels of a vehicle that is positioned upright on its wheels is a critical step to prevent any unintended movement during the rescue operation. By securely placing wedges or blocks against the wheels, it stabilizes the vehicle and minimizes the risk of it rolling or shifting unexpectedly, which could pose a serious threat to both responders and occupants inside.

Establishing a safety zone, gaining access through a window, or pulling occupants through a rear window are measures that are relevant in specific circumstances but do not directly address the immediate need to ensure the vehicle's stability. Stabilization is paramount, as it sets a safe working environment for the rescue team to operate effectively and safely, ensuring that personnel are protected from potential hazards that could arise from an unstable vehicle.