What happens after Bruno and Shmuel die in The Boy the Striped Pajamas?

In the book "The Boy in the Striped Pajamas," Bruno and Shmuel do not die. It is implied in the book that Bruno and Shmuel are taken away by the Nazis and likely die in the gas chambers, as the book ends abruptly with Bruno and Shmuel holding hands as they walk towards the gas chamber. However, the book does not explicitly depict their deaths.