The highest standard level of mutual aid or internal resource request for a major incident. Each alarm level brings a predetermined package of engines, trucks, and specialized units. By the fifth alarm, the incident has exhausted local resources, requiring massive logistical support, extended operations, and regional coordination.
Heard on the job
The warehouse blaze went to a five-alarm response before they could get enough water on it.
Insider tip
The exact number of units in an alarm assignment varies wildly by department, but a five-alarm fire always means maximum available deployment.