it is racing. the higher/faster the level you are competing on the worse the "worst case scenario" gets.
with that many carsinvolved i would think it was prolly the start or a restart that had everyone all bunched up. at that point all it takes is a slip of teh tires or a missed gear at teh front of teh field and the whole world is involved.
it sucks, but i am willing to bet that they will all be back soon. if you have the money to thrash cars like that you prolly have the money to fix them. or sell them to someone who can.
later
tim