There's not really enough Lithium in Li-ion or LiPo batteries to cause issues when putting out fires. The way the fire department here currently deals with electric car fires is to first douse the battery pack with large amounts of water to put out the fire and to then park the car in a container with water to keep the battery submerged as it cools[0]. No explosions as of yet.

[0] https://www.hvzeeland.nl/pictures/7/4/4/152447.jpg