I don't know, how often I have to repeat that: You don't have to kill those children. Just get rid of everything above and let them run to get help. Or let them run to get help in any case, you have to fight those enemies anyway. But no one forces you to kill those children, if you do that, it's your decision. Halsin will kill them, when he breaks free, but they are usually far away by that time, if you don't stop them.
So yeah, you decide, what you do here.
