The Nazi's began using the gas as early as 1934, they began a program to eliminate the people that were handicap,mentally ill. As they began their campaign to exterminate to kill the jewish population, they started to consider the gas as a better option rather than using bullets. The Einsatzgruppe, SS soldiers assigned the job to kill massive amounts of people at a time, found that they were mentally and physcially exhausted by killing through firing squads. The gas vans took less effort and were way cheaper than bullets. The specailly modified box trucks were sealed and had no windows, these trucks could hold up to 50 people at a time. The trucks would be backed up to a bulding and people would be loaded into the truck. The exhaust tailpipe was refitted into the bed of the truck. The toxic fumes would go in where all the people were. The trucks would just keep driving until everyone was dead. These gas vans were found to be very iffeciant and led to the development of stationary gas chambers.