You'll notice that one group of dudes is trying to walk away, while the other is just not willing to let it go. Even after a dude draws a knife, you've got that one big guy striding right at him with his chest thrown out in the posture of someone who's used to things going their way because of size and strength.
Oops.
One quick flick of the knife guy's hand and next thing you know, homie is bleeding out on the pavement. The thing that gets me is that he had to walk over to the guy in order to get hisself killed.
Ugly and completely avoidable. In the words of the great Warrior Poet, Humungus...