The American Psychological Association has assembled select resources for managing distress and building resilience in the wake of tragedy. Please visit the following link for the landing page to this information.
http://www.apa.org/school-shooting.aspx
In addition, Scholastic has published some articles about how to talk to children about this type of violence.
"Talking to Your Kids About Natural Disasters, War, and Violence" — an article offering advice from a child-development expert about how to talk with kids about violent, disturbing news.
http://link.scholastic.com/u.d?O4GjGXPUb7SrFD8cCg1tW=2721&cid=SN/e/20121214///CTadvice//////&ym_2MID=1455116&ym_2rid=20871742 is
"Talking to Children About Community Violence" — a tip sheet from the American Academy of Child & Adolescent Psychiatry about how to handle discussions with kids about violence in local communities.
http://link.scholastic.com/u.d?UYGjGXPUb7SrFD8cCg1tT=2731
I hope these resources are helpful in this difficult time. I wish you a happy and peaceful holiday,
Marge