SS Obersturmfhrer Kurt Gerstein, of the Institute for Hygiene of the Waffen-SS, during the war told a Swedish diplomat of life in a death camp, of how, on 19 August 1942, he arrived at Belzec extermination camp (which was equipped with carbon monoxide gas chambers) and was shown the unloading of 45 train cars filled with 6,700 Jews, many already dead, but the rest were marched naked to the gas chambers, where:
Unterscharfhrer Hackenholt was making great efforts to get the engine running. But it doesn't go. Captain Wirth comes up. I can see he is afraid, because I am present at a disaster. Yes, I see it all and I wait. My stopwatch showed it all, 50 minutes, 70 minutes, and the diesel [engine] did not start. The people wait inside the gas chambers. In vain. They can be heard weeping, "like in the synagogue", says Professor Pfannenstiel, his eyes glued to a window in the wooden door. Furious, Captain Wirth lashes the Ukrainian (Trawniki) assisting Hackenholt twelve, thirteen times, in the face. After 2 hours and 49 minutes the stopwatch recorded it all the diesel started. Up to that moment, the people shut up in those four crowded chambers were still alive, four times 750 persons, in four times 45 cubic meters. Another 25 minutes elapsed. Many were already dead, that could be seen through the small window, because an electric lamp inside lit up the chamber for a few moments. After 28 minutes, only a few were still alive. Finally, after 32 minutes, all were dead ... Dentists [then] hammered out gold teeth, bridges, and crowns. In the midst of them stood Captain Wirth. He was in his element, and, showing me a large can full of teeth, he said: "See, for yourself, the weight of that gold! It's only from yesterday, and the day before. You can't imagine what we find every day dollars, diamonds, gold. You'll see for yourself!" Kurt Gerstein
Auschwitz Camp Commandant Rudolf Hss reported that the first time Zyklon B gas was used on the Jews, many suspected they were to be killed despite having been deceived into believing they were to be deloused and then returned to the camp. As a result, the Nazis identified and isolated "difficult individuals" who might alert the prisoners, and removed them from the mass lest they incite revolt among the deceived majority of prisoners en route to the gas chambers. The "difficult" prisoners were led to a site out of view to be killed off discreetly.
A prisoner Sonderkommando (Special Detachment) effected in the processes of extermination; they encouraged the Jews to undress without a hint of what was about to happen. They accompanied them into the gas chambers outfitted to appear as shower rooms (with nonworking water nozzles, and tile walls); and remained with the victims until just before the chamber door closed. To psychologically maintain the "calming effect" of the delousing deception, an SS man stood at the door until the end. The Sonderkommando talked to the victims about life in the camp to pacify the suspicious ones, and hurried them inside; to that effect, they also assisted the aged and the very young in undressing.
To further persuade the prisoners that nothing harmful was happening, the Sonderkommando deceived them with small talk about friends or relations who had arrived in earlier transports. Many young mothers hid their infants beneath their piled clothes fearing that the delousing "disinfectant" might harm them. Camp Commandant Hss reported that the "men of the Special Detachment were particularly on the look-out for this", and encouraged the women to take their children into the "shower room". Likewise, the Sonderkommando comforted older children who might cry "because of the strangeness of being undressed in this fashion".
Yet, not every prisoner was deceived by such psychological tactics; Commandant Hss spoke of Jews "who either guessed, or knew, what awaited them, nevertheless ... [they] found the courage to joke with the children, to encourage them, despite the mortal terror visible in their own eyes". Some women would suddenly "give the most terrible shrieks while undressing, or tear their hair, or scream like maniacs"; the Sonderkommando immediately took them away for execution by shooting. In such circumstances, others, meaning to save themselves at the gas chamber's threshold, betrayed the identities and "revealed the addresses of those members of their race still in hiding".
Once the door of the filled gas chamber was sealed, pellets of Zyklon B were dropped through special holes in the roof. Regulations required that the Camp Commandant supervise the preparations, the gassing (through a peephole), and the aftermath looting of the corpses. Commandant Hss reported that the gassed victims "showed no signs of convulsion"; the Auschwitz camp physicians attributed that to the "paralyzing effect on the lungs" of the Zyklon-B gas, which killed before the victim began suffering convulsions.
As a matter of political training, some high-ranked Nazi Party leaders and SS officers were sent to AuschwitzBirkenau to witness the gassings; Hss reported that "all were deeply impressed by what they saw ... [yet some] ... who had previously spoken most loudly, about the necessity for this extermination, fell silent once they had actually seen the 'final solution of the Jewish problem'." As the Auschwitz Camp Commandant Rudolf Hss justified the extermination by explaining the need for "the iron determination with which we must carry out Hitler's orders"; yet saw that even "[Adolf] Eichmann, who certainly [was] tough enough, had no wish to change places with me."