Main Characters Opening Narration 21 main appearances Lieutenant Holly Sherman 13 main appearances Emergency Medical Technician 13 main appearances Captain Keeley Williams 11 main appearances Emergency Medical Technician 6 main appearances Emergency Medical Technician 6 main appearances Police Officer 6 main appearances Police Officer 6 main appearances Firefighter / EMT 5 main appearances Police Officer 4 main appearances Firefighter / EMT 4 main appearances Police Officer 3 main appearances Emergency Medical Technician 3 main appearances Police Officer 3 main appearances Police Officer 3 main appearances Emergency Medical Technician 3 main appearances Police Officer 2 main appearances Emergency Medical Technician 2 main appearances Police Officer 2 main appearances Emergency Medical Technician Police Officer 1 main appearances Firefighter 1 main appearances Firefighter