What are the four stages of fire?

• A. Incipient, Growth, Fully developed, and Decay
• B. Ignition, Flame, Smoke, Rescue
• C. Beginning, Middle, Peak, End
• D. Origin, Spread, Suppression, Extinction

Answer: (A)

Fire developing through a structure follows a predictable progression that helps firefighters anticipate hazards and choose tactics. The four stages are Incipient, Growth, Fully Developed, and Decay.

In the Incipient stage, ignition has just occurred and flames are small; heat and hot gases begin to accumulate, and early suppression or ventilation can stop the fire from growing. The Growth stage sees rapid spread as more fuels catch fire; flames extend, temperatures rise, and visibility drops due to increasing smoke. When all available combustibles in the compartment are involved, the fire reaches the Fully Developed stage, the period of greatest heat release and danger, where flashover and untenable temperatures are major risks. Finally, the Decay stage occurs as fuel is consumed or oxygen becomes limiting, temperatures drop and the fire begins to burn out, though hazards and smoke still persist.

These terms are the standard way the fire service describes how a fire evolves, which is why this option is the best choice. The other sets mix actions or stages not used to describe development—one includes rescue, which isn’t a stage of fire growth; another uses generic or unrelated terms; and another references incident actions rather than how the fire itself progresses.