How to tell two boys of 6 and 4 years old about death and the lost of their grandmother?

This was a shock for everyone in this family.
She left her parents, husband, child and grandchild, who were really close to her still very young grandmother… I feel deply for this family grief and I know they are still wondering how they are going to tell their young kids about this terrible news.
There’s nothing I can do and I couldn’t even find the strength to say anything to them directly, but I wish I could help this family out with some good advice from fluther.