You have a long track with difficult communication, many different flags and slow zones, and drivers of all levels of ability, or lack thereof. All of that came together in this one crash at the 24 Hours of the Nurburgring yesterday.
A driver in a Dodge Viper (from an experienced team) appears to miss the yellow flags at the end of his slow zone and barrels into the back of another driver in a Mini. That or the Viper driver somehow saw the up-ahead green flag too early.
As 'Ring experts Bridge to Gantry explain, the guy was barred from re-entering the race.
(Hat tip to McNewbie!)