Gas Vans were an addition to the many gas chambers used to eliminate the Jews. These mobile chambers were equipped with air tight compartments that were loaded up with people. From there the exhaust fumes from the engine were pumped into the van. The carbon monoxide caused suffocation and also monoxide poisoning which resulted in death. The gas van was invented by the Soviet Union in 1936 by Isay Berg. Before gas chambers and vans the victims were shot one by one. This was too much for the executioners so the solution was to tie up multiple of them, plug their mouths and throw them inside an enclosed van disguised as a bread truck.
When 70 –90 people were inside the vehicle, the doors were closed and the loaded truck headed for the furnace located 200 meters away. While travelling Laabs the driver left the vent open so that the exhaust gases passed into the sealed compartment and killed the people inside in about six minutes.
Because the size of the van allowed many to fit, this was saw as a way to kill many Jews at once.
Diesel Bus Chamber
This was not a quiet process, the drivers could hear the victims' screams, which they found distracting and disturbing.