Hey,
my information is that every departemet has its own laws for lights on the personal vehicle.
From green lights:
http://www.youtube.com/watch?v=YNGQYmJwhWE
over blue lights (I think espacialy for EMS personal):
http://www.youtube.com/watch?v=PqLIBb2Yh_M
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in some cases there are sirens, in others the fire personal does only have airhorns, in other depts.
they have sirens:
http://www.youtube.com/watch?v=bK-fav44uYw
and the red/ white ones like Erics Pov:
http://www.youtube.com/watch?v=Q_3z_...249F8&index=48
i know just a few depts. where blue and red is allowed like this :
http://www.youtube.com/watch?v=UVMtjOhvnUM
.........................
So some information at the end, when fire personal is responding to the scene they have to run the sirene at all time.
Hope that it will help you!
Regards
Philipp