First you should know -- experts say there's no right or wrong answer here. This is definitely not an easy topic to approach and some parents believe it's important that their kids hear it from them first. Others say it would only make their children -- if too young -- too anxious.
Dr. Glenn Saxe, Chairman of the Department of Child and Adolescent Psychiatry at NYU says the most important thing parents can do after something bad happens, or they see something bad on the news, is provide reassurance.
He says that kids reassurance that they and the people close to them are going to be okay. Tell them that you are doing everything you can to keep them safe but Saxe cautions, don't give false assurances. be real and truthful.
Parenting.com has some additional suggestions that may help parents decide how best to talk to their children.
First, wait until they are older, about seven years old and only get in to the "tough stuff" if they bring it up first.
Keep it black and white and younger kids will especially need reassurance that whatever they've seen won't happen to them.
It is also good time to bring up school safety procedures.
And perhaps most important of all, don't judge their feelings. Say it's ok to feel whatever they feel.