“It must have been a catastrophic failure”
The story said debris spread five miles. Sounds as if something came apart
The NY Times report says a wing came down a mile away from the main impact site:
https://www.nytimes.com/2017/07/10/us/military-plane-crashes-mississippi-delta-deaths.html
Possibly a propeller let go mid-flight. It has happened.
I flew on the EC-130H Compass Call aircraft back in the early '90s. We had two rows of equipment lining the sides of the aircraft. I almost always sat in the fore-most starboard position on that equipment, and to my left, somewhere about a foot or so, there was a safety tape (black/yellow) line up the inside of the fuselage that showed where the inner starboard engine's propeller would be. Basically I was told that's where to expect the impact should a propeller from that engine let loose and come into the craft.