What is a critical action to take when fire spreads rapidly?

Sealing off affected areas is a critical action when fire spreads rapidly because it helps to contain the fire and prevent it from spreading to other parts of a building or area. By isolating the fire, you limit the availability of oxygen and can reduce the overall impact and spread of flames. This action also creates a safer environment for both those inside the building and responders, as it can help contain hazardous smoke and toxic gases from escaping.

While retreating to safety, attempting to extinguish the fire, or calling for support are certainly important actions under different circumstances, sealing off affected areas directly addresses the immediate threat posed by a rapidly spreading fire. It essentially buys time for occupants to evacuate and for firefighters to arrive and address the situation more effectively.