What indicates that a vehicle is an emergency service vehicle?

An emergency service vehicle is typically indicated by its use of specific lighting systems which are designated for different types of responses. Flashing blue lights are commonly used by police vehicles, while red lights are often associated with fire services. Flashing green beacons, however, are primarily used by paramedics and medical responders. Therefore, while each color serves a particular function in signaling different emergency services, flashing green beacons, when seen, immediately indicate a health-related emergency vehicle, making them a distinctive marker for that specific role.

The inclusion of the other colors, such as flashing red or blue, aligns with their respective services, but they do not singularly define a vehicle as an emergency service vehicle in the way that green beacons do for medical assistance. Thus, flashing green beacons specifically signal the presence of a medical emergency service vehicle, making it a key identifier among the options given.