That is so sad...
What a tragedy for the family. It is always so shocking when someone sees no other way out than to take their own life. Desparation is a terrible thing. But the people left behind get marked for life by it, and that is the real tragedy.
Courage to you and the school in helping the children get through this. You know even if you don't tell them they will find out. It may be better coming from you, along with a discussion about how sad people can be sometimes, but how it's always so much better to talk to someone and try to work things out. It's amazing what children can learn from things like this, provided they are spoken to carefully and honestly.
Good luck, honey.