Why does Hannah decided not to tell the women any more about what to expect in the camp?

In the book The Devil's Arithmetic, the young Hannah Stern is taken back in time, and realizes pretty quickly that she is now living through the Holocaust. Because she's Jewish and has family members who survived the Holocaust, she knows all about what happened during this period of tragedy. 
When she and other guests at a Jewish wedding are forced by Nazis onto an overcrowded train, going to an unknown destination, Hannah knows that they are being taken to a concentration camp. At first, she tries to tell others about the terrible things she knows will probably happen at the concentration camp, to give them some sort of warning. However, she soon realizes that this is only scaring people even more, and doing more harm than good.