Federation Security and Emergency was an emergency response service, staffed by Starfleet personnel, which responded to civilian medical emergencies. As a young girl, Inana Skanda contacted Federation Security and Emergency after finding her grandmother, Gemma, collapsed on the floor of her home. (CoE eBook: Remembrance of Things Past, Book I)

It is not specified where this service is used, though it presumably would be in locations where a local civilian police force or paramedic service was not available.
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