In that wrongly wired portion of my brain I have my own thoughts on ending gangs very quickly. Small group of well armed men with big balls. Put us in the worse part of town, walk up to the first gang member you spot and shoot him in the face. Then follow that up with an ambush at his funeral where you eliminate the rest of them in one quick swoop. Suddenly they would get the hint we aren't playing and would quickly change their ways. Play the game they know.

Seriously though it needs to be a multi dimensional approach, IMO it starts with the adults, the parents and spreads from there.