Animals do that all the time. Dogs are known to tear their dead owners all apart when trying to wake them up. Some people say, that swans sometimes commit suicide, when their pair dies. Nature is interesting.
That asian guy doesn't look like gangsta at all. He looks more like nerd. Also - he didn't even try to defend himself. Well gangstas when they are alone are usually cowards, but they at least use swearwords. He looks peaceful.
Anyway, shit like this happens every day, when i was 12 years old, me and my classmates did all the same shit. Well, it's sad, but i grew up a little, and realized it's wrong, and they didn't. +12yo's punches are much weaker. I'm sorry for that dude, but it's just the reality. Streets are full of ****tards, but no one takes care of them at all.