A "personal drone" that crashed and burst into flames was the cause of the Kendrick Fire, a 335 acre fire in the Coconino National Forest (wikipedia: https://en.wikipedia.org/wiki/Coconino_National_Forest) in northern Arizona, USA. Coconino National Forest spokesman George Jozens said that about 30 firefighters from the U.S. Forest Service and Summit Fire and Medical worked to quell the fire.
(Score: 5, Informative) by tonyPick on Saturday March 10 2018, @09:31AM
Batteries, especially the LiPo packs you'll see in drones (high density, low weight, cheap) are made of fairly nasty chemicals that react very badly with each other, and the protection circuitry you'll see on them is there to attempt to minimise spontaneous explosions/overtemp/chemical fires that will result when charging, discharging or just sitting in a room (OK not quite that bad, but nastier than most people are aware of).
Assuming the drone crashed and the cell was punctured on impact then it's a definite "will catch fire" situation.