My daughters' dad passed away. How do I tell them?

This is a question I am posting for my sister:Yesterday I received a call that my daughters' (6 and 7) dad passed away from an OD. They usually see him every weekend, but when we tried to drop them off yesterday we couldn't find him. Turns out he was already gone. How do I tell them that their dad is gone? When my dad passed away a year ago they took it so hard, they loved their grandpa. I don't know how to go about telling them today. My sister will be there with me and probably doing most of the talking. We already know that we won't go into details of the drug use but we just need advice how to go about it all. via /r/Parenting http://bit.ly/2RBFW5K