Eli5 what are second and third alarm fires


I see in the news like second and third alarm fire alarms, I’m not from the USA, so I have no experience (that I’m aware of) of different alarm fires

In: 3

They refer to the intensity of the fire/how easily they are combatted. 2 alarm is used for house fires that are more manageable than 3 alarm house fires.

That refers to the number of engine companies (teams of firefighters) that are called to the scene to fight the fire

It’s just a measure of severity so the firefighters can bring an appropriate amount of equipment and firefighters. It goes up to 5 alarm which would be most severe.

Alarm refers to response package or what type of units and how many are are going to a fire based on department rules. Ex. Operating procedure states that five engines, a ladder truck, rescue, and three chiefs is for a multifamily residential fire.

Command on scene can add additional “alarms” or response packages depending on severity of fire. Say it’s a big fire and they need more resources, they can call for another alarm aka response package.