As of this morning, the 18 yr old is still in critical condition.
Also, I live in Carrollton, My wife works at a DISD middle school. she tells me stories of how kids act up and being disrespectful. but she says she care because most of her kids are good kids and want to go to college and better themselves. This will probably be her last yr there. It's very hard to get good quality teachers and coaches in that district. A lot of parents are moving their kids to the burbs.
Another thing, this not a normal thing that happens at DISD events. So, no the kids are not use to this happening. there have been more shooting at church or grocery store than at a DISD or FWISD event.