In the state of Missouri, to be considered an emergency vehicle, the vehicle must have a combination of red and blue lights.
It's it an interesting question and I can only surmise is that is done to catch the eye both night and day.
You know the difference between a job and a duty? A job you can refuse to do because it's dangerous; a duty you must do even if it is dangerous.
Normandy Officer Amanda K. Cates DSN 215 Killed 08/29/2006 Rest in peace kiddo you were loved and will be missed terribly. Justice is coming.