Thirteen year old ex hostage Kristina Dzagoeva kept a diary during her 52 hours of captivity. Parts of it were published in the German newspaper Bild and posted by utro.ru.
I translated the parts made available by utro.ru below (my comments in brackets):
On September 1st, when we stood in the school's court yard, not five minutes have passed [since the first day of school ceremony began] we heard the first gunshot. One woman screamed "They are attacking the school!"...
When we were sitting in the gym with our parents, the people in masks collected everybody's bags and cell phones. They also took earrings and necklaces with cross pendants. There were infants in the gym, as well as older kids. When we were just brought in to the gym, they set up mines right away. Some mines they put on chairs and some they suspended from wires on the sides and the center of the gym. There were 12 mines all together. The first day was good, they gave us water to drink and let us use the bathroom.
They gave us water, but let us use the bathroom less frequently. They said that they will shoot anyone who screams. They took some men and shot them one after another. They told their women to kill anyone on whom they would find anything [cell phones,etc]. They shot at anyone who walked too close to them. They let those with infants go. It rained pretty hard and that night no one has slept, we just sat there.
Aushev [ex President of Ingushetia and one of the negotiators] came. He said "Don't worry, we'll save you"... My younger sister Zera kept on asking my mother: 'When will the president come and get us out of here? I can't any more, I am hungry and thirsty".. Since, the president never came, they killed my sister and now I only have my mother and father".
Kristina's younger sister Zera was only 10 years old. Kristina's mother survived, and her father was not in the school with them.