If you’re not sure what to do to extinguish a fire in your vehicle, you should:

Use the Right Fire Extinguisher
The B:C type fire extinguisher is designed to work on electrical fires and burning liquids.
The A:B:C type is designed to work on burning wood, paper, and cloth as well.
Water can be used on wood, paper, or cloth, but don't use water on an electrical fire (can cause shock) or a gasoline fire (it will spread the flames).
A burning tire must be cooled. Lots of water may be required.
If you're not sure what to use, especially on a hazardous materials fire, wait for firefighters.
Position yourself upwind. Let the wind carry the extinguisher to the fire.
Continue until whatever was burning has been cooled. Absence of smoke or flame does not mean the fire cannot restart.
[Commercial Driver Handbook]