From early reports, it doesn't sound like Amazon had a warehouse manager monitoring the weather to warn employees and didn't herd all the employees towards the building's storm shelter. (Did it have one?) Hours of tornado warns as a line of 4+ almost continual tor warn boxes worked across metro St. Louis for hours before the warehouse was hit. I'm almost certain Edwardsville was under a tor warn at the time of the warehouse hit. Pretty sure Amazon was aware of the tornado situation and how it could impact their trucking ops.
It's early, we'll see what other info comes out. But this may end up being a modern equivalent of the Triangle Shirtwaist Factory.
In contrast to Amazon, reports are that the Mayfield factory has 100 workers trapped, but in the basement shelter.