Several theories being bandied about right now.
Nitrate processing plant.
Grain elevator.
Tanker fueling/defueling.
Weapons/fireworks raw materials warehouse.
I’m leaning towards that last one judging from how the smaller initial fire appeared to have bright phosphorous/magnesium streaks. There was another Twitter video, from a now most likely deceased camera person, from right across the street showing stuff cooking off before the big blast.
I am with you on that.
The blast went off way to large to be the others.
I would bet that the terrorists had a stash in with the rest of the fireworks to hide it and it all went off at once after the fire got to it.