What happens to many of the young children taken by the Germans from from Srodula while that are en route to Auschwitz?

All the children in Srodula are rounded up to be killed, and the parents are glad that they have sent their son away, but the Zawiercie ghetto is liquidated shortly thereafter. Rather than be sent to the gas chambers, Tosha poisons herself, her children, and Richieu. Vladek and Anja are not made aware of this until much later.