Looking at the direction or travel of the rest of the aircraft, I would say total loss of elevator control or problem with the pilot forcing the nose down :-/
Either way, a sad day

Indeed, looking at the pictures, it appears the elevator stab became detached. At 500mph this can, apparently, cause an immediate 10g nose-up attitude which can render the pilot unconcious and/or break neck. There is a photo which shows the aircarft nose-down, but no sign of the pilot's helmet, indicating (possibly) that he was out of it and face down. Sepeculation, I admit, but having read the opinions of pilots, this would seem most likely.
A tragic accident, but neither pilots nor spectators would be excited by planes dawdling around. I hope it doesn't lead to a ban on air races, but I expect it will. 
Compared to the airshows of the 80's and 90's and what the aircraft are really capable of, the shows nowdays are very tame.
Its a balancing act between thrilling the public and protecting them.
Its a hard one for me because i know and have seen what some of the aircraft can do today and loved every second of it.
Then again, I have worked with pilots who have lost there life in accidents and I have also walked round a field with a bin liner after one of these accidents

But at the end of the day ................. pilots live to fly and I have been told many times ( after lots of alchohol on both sides ) that if you've got too go ...............
Thoughts with the familys of the deceased
