When I say the gun powder was “set off”, I mean ignited. It is difficult to obtain an actual explosion from modern gunpowder. It is designed, to just burn very rapidly.
If the gases from the burning are contained, you can get a very low level explosion, similar to that of a propane explosion.
“It is designed, to just burn very rapidly.”
should be:
It is designed to burn very rapidly, rather than to detonate. Modern gunpowders are propellants, not explosives.
If it was gunpowder stored in cans and you had an initial flash fire from powder in the open the heat might cause the cans to cook off and explode or burn like a flaming fountain, maybe with a “747” roar.