The Norwegian Directorate for Education and Training has compiled good advice on how to talk to children and young people about war and fear.
When faced with difficult topics, it is important not to leave children and young people to their own imagination. Avoiding certain questions or giving incomplete answers can lead to unnecessary anxiety and confusion. Adults should create a safe climate where children and young people can ask questions and express their feelings. Adults should answer all questions honestly and directly, but also be open to the fact that you do not have all the answers.
Read more on the Norwegian Directorate for Education and Training's website (norwegian).