Decades later I was teaching preschool and asked the kids in my pre-K class what they wanted to be when they grew up. One little girl said she wanted to be God, and when I explained that was impossible she began to cry desperately hard. She sobbed for so long we had to call her mother to come get her. It turned out that child was actually grieving for her father, who had died many months earlier. She had planned to become God someday so she could make sure nobody else's father ever died, and maybe get her own father back.
Apparently it's normal for children suddenly to be hit by strong grief a long time after the losses they experience. This is a healthy thing for them, and part of the healing process. Perhaps reading a book about death to a child, or encouraging them to read one themselves, at least six months after a death in their family happens would help them recover from the tragedy.