EVs don’t combust spontaneously. If the battery of an EV is compromised or battery pack is pierced and lithium is exposed to air. Then that violent reaction (lithium oxidizing the air) will produce the fire you see.

I think this is from a training exercise though. Suspiciously empty lot. Some branding on vehicle might indicate test site. The idea here is that by covering the vehicle with the fire resistant blanket, the fire will consume all of the oxygen and eventually put it self out.