You can read about it here:
Nine bicyclists in a Critical Mass ride event in Porto Alegre, Brazil, were injured after a driver in a VW Golf car drove into the group at high-speed. According to Sky News, the driver of the car, 47-year-old Richard Neis, has been apprehended by police and is claiming self-defense after being threatened by some of the cyclists.
This makes Seattle's Critical Mass dustups look like a feisty game of Rock Paper Scissors. (Thanks to Slog tipper Bob.)