My uneducated guess is ammonium nitrate. That stuff has been know to cause huge explosions with big pressure waves in the past. Could’ve started as a fireworks fire but spread into an area that stores fertilizer. Whatever it was, the explosion was massive in scale and power. Here is a pic I grabbed of twitter. The cars are overturned facing the epicentre. They were literally pulled toward the explosion from the vacuum created by the blast. That’s a beast. #NovaScotiaStrong