A fire that becomes uncontrollable or expands outside its intended boundaries.
- For example, a fire set intentionally to burn brush becomes hostile if it spreads to other property; likewise, a fire that becomes much hotter than it is supposed to be or that cannot be extinguished is hostile even if it never spreads from the location where it was intentionally kindled.
A fire can begin as a friendly fire, but becomes hostile when it becomes uncontrollable and beyond its intended area.