District fire departments shall have the right of way on public highways, both inside and outside city limits, when going to or returning from a fire when operating under this act: Provided, The vehicle is equipped with a fire siren in good working order and the siren is sounded at frequent intervals and always two hundred feet before reaching any intersection of highways: And provided further, Such vehicle is painted red. Such right of way shall also extend to the use of the highway when fighting fires.