[apache]

Here is my assumption on what happened to it, simply based on the descriptions of what people saw. My guess is that a few blades, or possibly even a full disk broke off and were shot through the wing, igniting fuel and causing the engine to vibrate heavily, as well as tearing up the wing, and probably the fuselage too. The engine vibrations then shook the engine off the wing (they are designed to do that, so the engine shakes off the wing instead of the whole wing shaking off the plane), while the rest of the fuel caught fire and the plane became one big fireball. What caused it? Probably a lack of maintainance, or just poor maintainance on the blades didn't find that a few of them were cracked or should have otherwise been replaced. I highly doubt it was a terrorist act.