My son was just suspended from school for 3 days. He and 8 other kids were "body shop"ing, teen fighting.?

Imagine a 'fight club' where the only rule is that you can't hit in the face, where you beat your opponent until he 'gives up'. I am now faced with the daunting task of convincing a 12-year-old that this practice is dangerous, wrong, and above all, very stupid. Are there any doented cases where 'body shop'ing has caused serious injury or death? I don't want my kid to be a statistic in this or make any of his 'friends' statistics.