Ban fertilizer... think of the former children
This appears to be a BLEVE-boiling liquid expanding vapor explosion.
There are what appears to be two 8,000 ish gallon tanks that could have propane in them. they would have been heated up by the fire and BLEVE'd. The blast is typical of that amout of propane going boom.
Normally those tanks are over 100 feet from any buildings, but these were right up against the building on fire.
The wild card is what was in the building. Some have explosion proof rooms with special electrical when mixing chemicals, but the buildings don't look like those types. Could have been a electrical issue but that area doesn't blow up like that if they are doing things right.
Everything points to bleve from what I can tell from the overhead pictures.
Look, I know they never thought of it, but anyone who thinks it's a good idea to hang out recording a fire at an industrial plant....well, a lot of people thought that ship accident in Halifax Harbor was neat to watch too:
Halifax Explosion - Wikipedia, the free encyclopedia
A safe distance is way the heck away from whatever is going on.
Almost 10% of West has been killed or injured by this. We have 1 employee with family killed (first responder) and another with a family member seriously injured. Another 9 have serious property damage or complete loss. We gave up a hangar so the responders could set up their staging area; airplanes are out on the Tarmac.
Turning out better than would be expected here; not good, but could be much worse. The city of Waco has really stepped up to support West. Lots of people offering up their homes to strangers. Some construction companies are offering free services to make homes livable quickly. Huge linesmen blood donations.
Keep in mind, our closest level 1 trama center is in Dallas (1.5 hours north). And there's only 1 there. I believe Boston has 3 or 4, by comparison.
Personal update: my family is completely unaffected. We're 30miles south (furthest part of Waco from West), didn't hear it inside the house.
If they are certain of this I am wondering how long they have actually known.
Maybe somebody 'fessed up.