Wildfire

n.	1.	A composition of inflammable materials, which, kindled, is very hard to quench; Greek fire. Brimstone, pitch, wildfire . . . burn cruelly, and hard to quench. - Bacon.
	2.	(Med.) An old name for erysipelas.
	3.	A sort of lightning unaccompanied by thunder.

Noun

1.

wildfire - a raging and rapidly spreading conflagration

conflagration, inferno