A signaling system for mounting to an exterior surface of an emergency vehicle opposite an interior surface of the vehicle to which objects are mounted is provided. The signaling system includes a light bar having a plurality of signaling devices supported on and distributed along a base member and enclosed by a cover. A plate is secured to the exterior surface of the emergency vehicle by one or more fasteners of a first type, which pass through the vehicle into its interior. The plate includes a surface for engaging the base of the light bar such that the light bar can be suspended from the plate. An opening is provided in the plate for communicating electrical wiring to the light bar. One or more fasteners of a second type that do not pass through the surface of the vehicle into its interior are provided for securing the light bar to the plate and thereby the exterior surface of the emergency vehicle such that the light bar can be removed from the exterior surface of the vehicle without removing the fasteners of the first type, which hold the plate to the vehicle.