Hi Barbara,
The link to Fred Rogers' advice appears to have moved to this new location: http://www.fredrogers.org/FRC/par-tragic-events.html.

Here are more helpful resources I found:

1). PBS Parents: Talking with Kids about the news -
http://www.pbs.org/parents/talkingwithkids/news/talking.html

2). A nice post from Gabriel Hershman -
http://reviewsmylife.com/death-and-other-dastardly-ds/

3). National Association of School Psycologists: Talking to kids about violence - http://www.nasponline.org/resources/crisis_safety/talkingviolence.pdf