I was there, and also took some photos. I have no problems posting them when there are no serious injuries or deaths, but they don't really show a lot more than the press photos.
There's some discussion at
reddit, which also contains a link to more photos, but not much is known.
The Jodel (model 1050, built in 1959) veered to the left early in the takeoff run during the day's second mass-departure, and crashed into the (1956 vintage) Cessna 172, with maybe 30 more aircraft waiting on the taxiways on either side of the 1300 m grass runway. The first part of the runway has quite some incline, so acceleration of the Jodel, which isn't exactly over-powered in the first place, was relatively slow. The reason
why it went left is unknown, winds were low, and although the runway has some bumps, none are bad enough to cause such a diversion.
All operations were suspended for over an hour. Departures resumed from the western part of the runway, and later from the entire runway, but there were no more landings and the airshow was cancelled completely.
The accident area was cordoned off, BFU personnel have been looking at the scene, and my assumption is that the specialist investigators will arrive today to take a close look and decide what to do with the wreckage. The BFU website is notoriously low on details (i. e. there are none), and I don't expect any information until their next Bulletin. Since no-one was seriously hurt, they may even chose only to publish a factual report without any analysis of the causes. We'll see.
Cheers,
Bernd