The worst accident I was involved in was in high school. A buddy of mine was driving and we were pulling out from a gas station after leaving school and filling up. He just completely ran a red light, for no reason. I was screaming at him too... RED LIGHT RED LIGHT! And he just plowed through. The scariest thing was seeing this poor lady in her station wagon about to be T-boned by us... with a small child in the rear seat.
I'll never forget the look on that kids face or the fear that we were about to smash head-on into him. Luckily my buddy swerved at the last minute and we hit a telephone poll head on instead.
We weren't going very fast... maybe 35, but it totaled the car. Everyone was ok, though.