Everyone probably heard noises about the 17 year old American kid who shot and killed somebody in the middle of one of the riots. He killed 2 people. One of them was lunging at him to try and take his gun. That one is an easy self defense. Edit: The first guy was also trying to take his gun. So this is self defense too.
Its actually a dramatic story.
This video explains the whole case.
IMO the kid was playing a very very dangerous game. But he isn't guilty of murder though. Not in the USA sense. You know.. guns, fuck yeah.