Whew, after reading all these stories, all I can say is I thank God my kids grew up in a small town. Around here in rural east Texas, the closest thing to true gang activity of any magnitude (as opposed to "wannabe" gang activity) is in the Hispanic community and seems to be a carry over from Mexico. Not that that's not bad - in fact it's AWFUL - but it's pretty limited to hispanic-on-hispanic violence.
It is however a terrible and fairly new element in our society, directly related to the rampant drug culture and drug war lord power struggles just across the border, and occasionally that culture of violence bleeds over into "gringo" culture (and by that I mean simply American - not just white - culture) locally.
In the local high schools, and in neighborhoods dominated by immigrants, illegal and otherwise, from Mexico, gang activity does run rampant. Yet another reason why we need to do more to secure our borders.