In case you weren't sure, black powder is extremely flammable, as this video proves.
The shooter fires a black powder rifle over a table with exposed ammunition.
Watch as the resulting fireball engulfs him in this epic video fail.
This shooter fires off a muzzleloading rifle and makes a terrible error. He has exposed blackpowder that then ignites on the gun range shooting table. The result is a huge fireball that catches this shooter off guard and sure must have hurt.
Care must be taken when especially working with black powder. This is what happens when a shooter gets sloppy on range safety.