I was driving down the road at approx. 20 - 30 mph. there was a vehicle in front of me. as the light turned from yellow to red, first it was going to go through the light but then stopped. i slammed on my brakes and the abs brakes did not work. my brakes locked and i skidded. fortunately, the vehicle in front of me heard me squealing, and started easing forward. it happened to be a truck with a receiver hitch on the back. that's what i hit, pushing him into the intersection. he was not hit. the person i hit turned out to be a policeman. *tr