We left the airshow just after it happened. The Firefly had just done one pass and was repositioning for another pass. Then all we saw was a dust cloud rising up. Shortly after, smoke was seen coming from the crash site. (Note, it was not visible to the crowd at Duxford).
Then the sounds of sirens and the commentator saying that the show was temporarily suspended.
My condolences to the family and friends of the pilot and his passenger.