Sorry it was NOT a J 170 as I put in the post. It was a 450UL about 7 years old. First reports were of a loud bang and I think this got translated to an explosion. But the latest news of the wing becoming detatched seems to be the most likely.
But this has yet to be confirmed.
A J170 crashed in France last week killing both pilot and passenger (father and son), both British. Word has it that a wing became detatched from the body.
This has not been confirmed.