The AAP (American Academy of Pediatrics) has a excellent article with tips and resources to help parents talk about disasters with their children. Here is an exerpt from that article.
Talking to Children About Disasters
“Children can cope more effectively with a disaster when they feel they understand what is happening and what they can do to help protect themselves, family, and friends. Provide basic information to help them understand, without providing unnecessary details that may only alarm them.
For very young children, provide concrete explanations of what happened and how it will affect them (eg, a tree branch fell on electrical wires and that is why the lights don’t work). Let children know there are many people who are working to help them and their community to recover after a disaster (such as repair crews for the electric company, or firefighters, police, paramedics, or other emergency personnel). Share with them all of the steps that are being taken to keep them safe; children will often worry that a disaster will occur again.
Older children will likely want, and benefit from, additional information about the disaster and recovery efforts. No matter what age, start by asking children what they already know and what questions they have and use that as a guide for the conversation. Limit media coverage of the disaster—if children are going to watch media coverage, consider taping it (to allow adults to preview) and watch along with them to answer questions and help them process the information.“
To read the complete article click the following link.