Hopefully, there is a community crisis team that can provide services to any member of the community who is being affected by this incident. It's very common for people who even just live near the scene to have symptoms of acute traumatic stress disorder, which is basically PTSD that lasts no longer than a month. Many times, there are people who fly in to provide these services when there's a full scale disaster, such as a hurricane or earthquake, terror incident. I know that some of my professors do this.
As for the victims, they will intensive work with a trauma specialist.

I find that I am still feeling affected by this! I got really upset when I saw a facebook posting from one of my closest friends from college. She was raving about how "crazy it is to be in AZ right now, with all this football pre-game pep rally crap going on." Is she deaf, dumb, and blind? Of course, I didn't say anything, but instead focused on my one friend who is very politically connected with many of the people that Rep. Giffords works with, and listened to her assessment of the situation.