Children sometimes lack perspective of their world around them. They hear about something that happened in India while they live in Oslo, and they feel that this is happening ...next door. They cannot understand how big is the world or how far from them is what happened. They even think that if they move to another house, they will feel safe again. Listen to their need: safety. Reassure them that you will protect them whatever happens. Remind them that there are always good people around us, not only people that want to hurt us.
At the same time, you have the opportunity to learn what they heard and how they feel about it. Don't judge their feelings. Don't dismiss their fears. Accept and explore them. It's OK to feel sad. It's OK to feel scared. It's OK to feel confused. You are not expected to have a clear mind immediately after the shocking news. You as a parent CAN be sad as well. Sad, but calm. Children absorb all the emotions, so if you handle your sadness with a calm way, they will copy that. If, on the other hand, you deal with your sadness or fear, with a dramatic, over-expressing, catastrophizing way, then the children will absorb that, and they will act likewise. But for them, once they get onto that "vehicle", it's difficult to step off it. They will dream about it, think about it, get overwhelmed about and probably it will remain inside them as a quite traumatic experience.
Let the feelings flow. You don't have to talk about it. Draw it. Sing it. Tell stories about it. Playing is the easiest way for children to let their thoughts and feelings come out. Use that tool, and make the most out of it. It will surprise you how much you can learn.
Respect their developmental level. Young children don't need all the details of the terrible event. They only need to feel safe and secure again. Teenagers, on the other hand, they are looking for the details, because they want to rationalize their feelings and make sense out of what happened. Even they don't ask for you to talk to them about the news, don't assume they are OK. Initiate a discussion. Adjust to their needs and help them accordingly. They will respect and appreciate that.
After all the talking and the sharing takes place (even though sometimes you will need to come back to that because the children will have more questions...), provide some kind of closure to the children. Memorialize the lost people: make a drawing about that. Share stories. Light up candles and blow them, and at the same time blowing away the fear and the pain.
For bigger children, some action can me also therapeutic: help others, volunteer, keep routines. That way you remind them that life goes on. And that the Good will always win over the Bad.
Source: Child Mind Institute