'Relatives and colleagues of the six victims have called for new regulations that would require warehouses to have storm shelters to protect people during tornadoes. State lawmakers have not done that. In March the House passed a bill that would create a task force to study the issue, but that bill remains pending in the Senate.'
'The Edwardsville warehouse that was damaged by the tornado did not have a storm shelter. As part of the rebuilding process that started last summer, a shelter was not added to the building. Current code does not require warehouses to have storm shelters.'
Edit: TLDR, the warehouse is being rebuilt but without a storm shelter.
https://www.yahoo.com/news/one-tornado-killed-6-amazon-163834326.html