Okay I only ever seen this one single part of the film while I was getting ready to leave on vacation.

All I saw was a white girl and a black man standing together by a river. The guy was in military garb of some sort. There were three boys, seniors in HS or college, facing them. I think their hands were tied. The girl gave the man an approving look and he started to shoot the 3 white boys. I think one started to escape and dove in the water but he was still killed. I get a feeling the boys did something to the girl and this is how she got revenge or something. But no one spoke at all in the scene. I have utterly no idea when it was made.

Anyone know the film?