A specific use case I was thinking of is some local hotels that my company does IT for. Hotels have lots of third party systems embedded locally and service providers doing stuff for them. If the fire alarm sounds, I'm sure they would love to know about it so they can react faster, either for assisting with the immediate crisis or facilitating the recovery. As far as I can tell, the fire detection/alarm systems are stovepipes that don't tell any other systems (other than 911) what is going on.
One example of an existing use of this sort of thing, is that fire alarm systems commonly notify the building's lift controller, which sends the lift to the ground floor and opens the doors.
