Engines are your primary response vehicle to most Fire and EMS incidents. With their hoses, Wagon battery, and full compliment of 4 EMT trained members, they can provide numerous uses at an incident from fire suppression, extra manpower, traffic control and rescue. The ALS Engine with 1 Paramedic level trained member is also great for quick ALS responses . By having an ALS Engine and having a BLS ambulance transport, you do not deplete an area of ALS resources during the transportation and return phases. A good example of this is Station 2 in the game. By having an ALS engine and a BLS ambulance for transport, you do not tie up the ALS unit with the long drive to the hospital and back to the area, instead you just treat the patient until the BLS unit transports and you're immediately back in service for the next call be it a Fire, Accident, or anything else.
ALS = A Paramedic Assessment engine differs from a standard BLS engine in that one of its members is a Paramedic and the apparatus will carry a minor compliment of ALS/ACLS gear to provide rapid treatment and stabilization until an ambulance unit can arrive on scene.
BLS = A BLS engine differs from an ALS engine in that all of its members are only FF/EMT's and the apparatus will carry a minor compliment of BLS/BCLS gear to provide rapid treatment and stabilization until a full paramedic unit can arrive on scene.