I have a fire/riot/sickness in my town but I can’t mobilize extra emergency service as the interface is broken.
Sometimes the interfaces are also mixed up so that I see the hospital one for the fire station.
Try clicking on a different fire station to see if it goes away. If you don’t have another, restarting the game should also help with the issue.
You can just play on if it’s not urgent as the error will disappear on it’s own after a while.
The autonomous part of the emergency service is not affected by this bug.