The effect of the death or injury of any firefighter who is killed or injured outside the territorial limits of the county or municipality where the firefighter is a member of the fire-fighting force or fire department and while that force or department is functioning pursuant to any contract made under Section 11-7-1 shall be the same as if the firefighter were killed or injured while that force or department was functioning within its own territorial limits, and the firefighter’s death shall be considered in the line of duty.