Some of the children in Beslan must have known this, maybe just instinctively.
After the siege was over, I think hours later, a group of children was found hiding somewhere in the basement. They had hidden themselves right away and never went through what was going on upstairs.
I'm sure they didn't have any food, maybe there was water nearby for them though. But at least they didn't have to see what was going on, which will never leave the minds of the rest of the survivors.
A few days of real serious fear, survivor guilt, they'll have enough problems, even without being in the middle of the Hell the others went through.