The question should be answered by a specialist firefighter team based on proper documentation about which other substances are stored there.
Poor guys who went unprepared into a chemical storage facility, only equipped with water...
Firefighter won't able be know all places and what stored in building (legal or illegal) beforehand.
Factories/workshops/warehouses etc here are supposed to keep a updated copy of Material Safety Data Sheet (MSDS) or Safety Data Sheet (SDS) which can be folder which contain data sheet of all chemicals and dangerous substance stored (think it safety regulations in Singapore). In case fire, that's one of documents that suppose to bring out so Firefighter knows what is stored inside.
Normally have more than 1 copy, near the storages area, and eg in office (so staffs can bring out during emergency).
And at the guard post (likely with floor plan too).
China will someday get past all the quality control and shoddiness that is in their industries today but even then accidents and the such will still happen. It is only a matter of time to get a few generations under the belt to get rid of that country bumpkin edge they have now. I say this because looking at an early powerhouse America you had the same kind of huge industrial accidents like this explosion. We have evolved into just poisoning giant swaths of land/water like the Gulf of Mexico and the river that is currently full of old gold mining chemicals toxic as all get out. The Budweiser beer bottle plant in my town routinely ejects crap out their stacks that settles back down to the ground as white ash and man you ought to smell that stuff....gross. I would LOL if it was funny.