If the tail broke off, you lose all control, the plane could flop around and tumble in all three axes. This could cause the entire plane to break apart and scatter over a wide area, I suppose.
As for what the initial cause of the breakup was, I suspect we'll never know. Rumors will be thick in the air, I'm sure.
I suppose a analysis of the pieces might reveal if there was an explosion of some sort. Of course it depends on what people decide to reveal to the public.