A driver was injured by a group of cyclists Friday after several from the group became violent when he attempted to drive his vehicle through the mass of bicycle riders.

The group of bikers came together, as they do every last Friday in Seattle, to ride in a "Critical Mass Ride," which one web site says is an event "to celebrate cycling and to assert cyclists' right to the road."

In this case, the Seattle Times reported that some cyclists in the group became angered when the driver of a Subaru station wagon tried to pull out of a parking spot as the group of roughly 100 cyclists were riding by. A few in the group blocked the car from moving, and banged on it. The driver, outnumbered with only his girlfriend in the passenger seat, began to slowly back out when he bumped a cyclist, further enraging the group.

Several cyclists attacked the vehicle, shattering the windshield and back window. The driver pressed on, hitting another cyclist. He drove a little way, but was cornered again by the large angry mob. Reportedly, someone punched him through his open window, and another person slashed his tires before he got out of the vehicle. Upon getting out, someone hit him in the back of the head causing a gash.

Finally, police arrived and the crowd thinned. Two men were taken into custody for investigation of malicious mischief. Another man was questioned and released before being identified as the person who hit the driver in the head. Police are looking for him.

No cyclists or the driver's girlfriend were hurt. The driver's injuries were not life-threatening, but he was taken to the hospital.

According to a Critical Mass website, which states that there is no official CM website, "CM is intended to be a celebration, not an opportunity to cause trouble. Those who want to try to tie up traffic as much as possible and be confrontational with motorists are missing the point. We can assert our right to the road without being rude about it. Focus on the ride, not on the cars that also happen to be on the road."

The site also says that there are no central leaders or organizers of the rides.

The Seattle Times reported that some CM riders said they slashed the tires to prevent the driver from hitting any other cyclists.