Which of the following is considered the first step in gaining control of a building?

Gaining control of the stairs is crucial because stairs often provide access to multiple floors and sections of a building. Controlling the stairs ensures that firefighters can effectively manage their movement throughout the structure, allowing them to address fire spread, rescue operations, and ventilation strategies. This step facilitates both vertical and horizontal fire attack efforts, as firefighters need to access various levels to combat the fire and attend to any victims.

While controlling the main entrance is important for establishing a point of access, it does not provide the same strategic advantage as controlling the stairs, which can significantly influence firefighting operations within a multi-story building. Establishing a water supply and conducting a risk assessment are also vital components of the tactical approach, but they come into play after the initial control measures and are often dependent on first securing vertical movement within the structure. Therefore, controlling the stairs is the most critical first step in gaining overall control of a building during firefighting operations.