A reconstructed farmhouse, called the “Red House” according to the colour of the non-plastered bricks, but also Bunker I, serves as a gas chamber for the first time. Groups of Jewish inhabitants from Upper Silesia are gassed here. In the two chambers, it is possible to kill up to 800 people at once. The dead are buried into mass graves on the adjacent field, where huge open-air pits that can hold up to a thousand bodies are dug out. The system of mass murder begins to take shape.

After the deported arrive, the first thing that occurs is selection, where healthy men and women are accepted for work in the camp, as well as older children. Usually, this includes men of 16 to 45 years of age. With women, it is their relationship to their children that decides their fate: if they do not want to abandon them, they die with them. Pregnant women also go directly to the gas chamber, as well as all of those that do not pass through selection, i.e. those that are too old, too young, or too weak or ill.

At first, the people are driven into the gas chambers fully dressed, which soon changes. Undressing cadavers is not easy, and the clothing is damaged and soiled. Also, the undressing of the victims is time consuming, not to mention that naked people are more submissive. Gradually, a manual according to which the murdering takes place up until October 1944, when the last victims are gassed, is created.

The Nazis convince the people with their lies that they are being disinfected before entering the camp; they are forced to strip down in the courtyard of the crematorium, in front of the bunkers, and later in the dressing rooms, and then journey to their death. Often, the whole proceedings take place calmly; the Nazis are nice, polite, and attentive up until the airtight doors are closed shut.

Dying usually takes from five to fifteen minutes, depending on the number of people, the number of Zyklon B crystals thrown in, and the temperature, which must be 27 degrees Celsius for the crystals to evaporate.

Panic ensues in the chamber, the stronger individuals trample the weaker ones; many are bitten, are scratched, and have ripped their hair out in despair. Blood, vomit, excrements are on the floor. Bodies are literally intertwined. When the gas begins to choke the people, everyone starts to scream, some cry out “Sh’ma Yisreal”, which is a death prayer. The stronger ones try to get to the ceiling and to the doors, and so they climb over the weaker ones. Sometimes, they are literally flattened. The dead have usually defecated themselves, are blackened, black and blue, or red-coloured. Some have nosebleeds. Most children are literally attached to their parents, and mothers often hold their little ones in convulsive grips. It is not easy to separate the bodies from each other. Many have bloody fingers and broken fingernails as they scratched the doors and the walls.

Faeces, blood, urine, and vomit cover the ground, sometimes even gold items, rings or precious gems that the dying had hidden in their orifices, are also found.

After opening and airing out the chambers, the dead are pulled and mined out. Their orifices are searched for any valuables, their gold teeth are pulled, rings and earrings are taken, and their hair is cut.

After being cleaned out and washed, the chamber is ready for more victims. Sometimes, the bloody walls are whitewashed and the rooms are sprayed with fragrance. Both steps are attempts to cover up the last mass murder.

In the first phase, gassing is overseen by the pair of SS officers, Maximilian Grabner and thirty-six-year-old SS-Obersturmführer Franz Hössler