What gun or pistol did the Nazis use to kill multiple people with one bullet?

Most any rifle employed in the Second World War by any warring faction would have been capable of killing multiple persons, provided they were lined up correctly. The standard German service rifle of the time period was the Mauser Karabiner 98, which fired a 7.92x57 cartridge, and could very easily go through multiple persons. Medium machine guns of the German military used the same cartridge, but these rounds were fired in rapid succession.

Anti-partisan forces, death squads, and the like typically preferred rapid firing submachineguns for this task, however, such as the MP 38/40, or the Finnish Suomi M1931.