Except any sound before the initial explosion would be impossible. The meteor would be traveling faster than the speed of sound, the first thing felt or heard by anyone would be the light and heat of the explosion followed by the shockwave.

When anything combustible is aerosolized and mixed with oxygen, it allows it to explode. This is how thermobaric explosives work https://en.wikipedia.org/wiki/Thermobaric_weapon see also https://en.wikipedia.org/wiki/Dust_explosion

Gunpowder doesn't need oxygen, but it burns instead of exploding. If there was an initial set of fires and smaller explosions that dispersed unburned gunpowder and wood/grain dust into the sky, once it was dispersed a flash could have spread through the dust cloud and created a huge explosion as described. This theory would explain both the initial disturbances and the huge explosion at the end, but I don't see it mentioned anywhere.