That is true. But they usually don't have lots of artillery shells laying around that get launched out into the neighborhood when the building explodes.
The factory had lots of explosives, and the "story" now in Russian media is that they just made fireworks for display purposes. That still doesn't explain the shells. Or the scale of the secondary explosion.
Note the timing of the blasts in this video
You’ve got to be careful storing those metal pipes. The Russians should have taken precautions.
You’ve got to be careful storing those metal pipes. The Russians should have taken precautions.
Looks like a blockbuster.