From the article:
The ZIS-30 was amongst a handful of designs created by the Soviets as a stopgap measure in an attempt to stem the German tide after the opening phases of Operation Barbarossa. In August 1941 the design bureau at Gorky Factory no. 92 mounted the 57mm ZIS-2 gun onto the chassis of a Komsomolets artillery tractor. It proved a successful design and was quickly pressed into service.