A gas van or gas wagon (Russian: душегубка (dushegubka); German: Gaswagen) was a vehicle equipped as a mobile gas chamber. The vehicle had an air-tight compartment for victims, into which exhaust fumes were transmitted while the engine was running. The victims were gassed with carbon monoxide, resulting in death by monoxide poisoning and suffocation. The gas van was invented and used by the Soviet secret police NKVD in the late 1930s during the Great Purge.