Which stage of a fire indicates sustained combustion of all materials?

The fully developed stage of a fire represents the phase where combustion is sustained at its highest intensity, and all combustible materials within the fire's area are actively burning. At this stage, the heat and flames have reached their peak, leading to a maximum release of energy and the potential for a rapid fire spread.

In this stage, not only have the initial fuels ignited, but secondary fuels have also caught fire due to the elevated temperatures and heat transfer, creating a volatile situation characterized by high temperatures, intense flames, and a significant production of smoke and hazardous gases. Understanding this stage is crucial for fire protection personnel, as it requires immediate and effective action to contain and extinguish the fire to prevent further damage and endangerment to lives and property.