What is the only reliable method to ensure everyone has safely evacuated a building?

Conducting a thorough search of the building is the only reliable method to ensure that everyone has safely evacuated. This approach allows firefighters and incident commanders to verify the presence or absence of occupants in all areas of the structure, especially in places where people may be trapped or have difficulty evacuating. The thoroughness of this method ensures that no one is left behind, as it covers all potential hiding spots and areas that may be dangerous.

While questioning occupants, conducting a head count, or asking witnesses may provide some information about evacuees, these methods are prone to error. Occupants might not have accurate knowledge of who was still inside, and counting individuals post-evacuation can be unreliable if people enter or leave without being noticed. Witnesses, too, may not have a complete picture or might not have seen everyone who was in the building. Thus, a thorough search is imperative for the safety of all individuals involved.