what is a 7 alarm fire

In the United States and Canada, the term "alarm" is used to classify the seriousness of fires, indicating the level of response by local authorities. A "seven-alarm fire" is not a standard term used to describe fires, and there is no specific definition for it. The number of alarms in a fire refers to the number of resources, such as fire engines, trucks, chiefs, specialty units, and personnel, needed to manage an emergency incident. The more resources needed, the higher the alarm designation. For example, a one-alarm fire would typically be regarded as "less serious" than a two- or three-alarm fire, but even a one-alarm fire typically results in a significant deployment of resources. The exact numbers of resources deployed to a fire based on the number of alarms can vary from region to region.