You know the answer. Each city is home to a school where incredible acts of violence occurred. Teens slaughtering teens in random fashion. Your peers, seniors, gunning down their own classmates and teachers. And everyone wants to identify and point a finger at the cause.
Guns are too easily available.
There's not enough security on campus. Certainly, guns can be dangerous. But guns have always been available to children, in historical times, and especially in rural areas. Gun control is not the answer. Parents have always been authority figures against whom some teens will rebel, no matter how observant, sensitive or caring they are.