Pray for the souls of those you have lost so that God may rest their souls. That they will find peace and rest after this life of struggle and trouble.
It might be a hard thing to do especially if you are still in shock and struggling to believe they are gone, but in any case, the least you could do is to pray that they rest in the bosom of the lord.
Say this prayer:
Dear God, (person’s name) is gone, and my heart is broken but what can I do? I believe you know better than anyone else and you know what’s best for each one of us. I'm comforted in the fact that you love us all and you’ve good plans for us all.
I pray that (person’s name) will find rest and peace of mind in heaven, that the smiles on their face will be broader than it has ever been. I pray that all the worries and struggles of this world be forgotten and that they may rest in your bosom in peace, Amen.