Incipient is the stage from seeing flame until 4 minutes. Fire can be extinguished by a basic fire extinguisher, but the user must have been trained on how to use a fire extinguisher, so it is likely that the fire can be suppressed efficiently. However, in reality, those who witness the fire in its incipient stage are afraid of flame and temperatures over 400°C and do not get closer to extinguishing the fire, so the fire develops into a moderate and severe stage.

Moderate to severe is the stage the fire has started for 4-8 minutes. The temperature becomes over 500°C. To use a basic fire extinguisher, the user must have the expertise, and enough equipment must be available. An advanced and safe fire extinguishing system should be used to extinguish the fire. However, fire witnesses may be afraid and run away, so the fire evolves into a severe stage.