Police light bar

Police light bar,just as its name implies is mounted on police vehicles.
There’s different usage by country in emergency colors:
United States: Red and blue of lightbar is the most common in the United States but some areas like New England and the southern United States use predominately blue for Law Enforcement and only red for Fire and EMS. Canada: Red is the most common here but most places are switching over to red and blue for both Law Enforcement and Fire/EMS. Western Europe: Blue for all emergency vehicles. Argentina uses blue for police, red with some blue for fire, green for ambulances, and amber for utility vehicles.
Anyway, about most of countries are used red and blue as Police lightbar,Amber for utility vehicles.As for ambulance lightbar,different countries have different regulation.