Station 17 was a firefighting unit of the Gotham City Fire Department.
After Scarecrow forced a mass evacuation of Gotham by threatening to detonate a chemical bomb on Halloween Night, the Station 17 unit went out to try and put out a fire. However, their truck ended up stopped by rioters, and each member of the station ended up being held hostage.
In actuality, its Fire Chief, Raymond Underhill, had collaborated with Firefly to commit arson throughout the various fire departments while the other stations were cleared out in order to ensure that his unit was able to put out various fires and not become obsolete, due to the government shutting the fire department down due to not needing it. Underhill was then arrested for his involvement in Firefly's arson-related crimes and locked up in a maximum security prison after everyone in his unit was saved. Underhill felt remorse for his actions and willingly accepted the consequences.
After the attack on GCPD, the Station 17 crew members are nowhere to be found. It's possible that they were evacuated for various reasons, or that they simply headed back into the field, hoping to save more lives.