What term is used for a fire that is extensive and difficult to control, typically involving large fuel sources?

The term that is used for a fire that is extensive and difficult to control, typically involving large fuel sources, is "mass fire." This concept refers to fires that have grown to a size where they are challenging not just to manage but also to extinguish due to the volume of material that is burning. Mass fires can involve significant amounts of wood, vegetation, or other flammable substances, which contribute to their intensity and spread. Understanding mass fires is critical in fire management and prevention strategies, as they pose significant risks to both human safety and property. This term captures the severity and scale of such fires, making it a precise choice for this situation.