This is why it's parlous to ascribe everything that happens in the world to the will of God. You could just as easily shoot someone randomly through the head and excuse it by saying that if the person died it was God's will and so the responsibility was out of your hands.
Indeed: God is powerless to prevent a murderer from murdering someone!
By exercising His Divine Omnipotence, and interceding to prevent the murder, God would be restricting the Free Will of the Murderer - and that's a no-no.
Yet an innocent bystander who could have come to the aid of the potential murder victim - he is culpable of failure to render assistance.
Regards,