On August 27-28, 1941, near the Ukrainian city of Kamianets-Podilsky, SS General Friedrich Jeckeln oversaw the killing of 23,600 Jewish people in pursuit of Hitler’s Final Solution. This was their initial large-scale mass murder action. Most victims were former Czechoslovakian citizens (now stateless) and were loaded into freight cars by the Hungarian authority, dropped off in Kolomyia, forced to walk 102 miles to Kamianets-Podilsky where they were subsequently shot with automatic weapons.

The perpetrators did not make any attempt to hide their actions and witnesses did not interfere.

Photographs exist which show thousands of naked corpses piled into open pits.

Further Reading https://www.yadvashem.org/untoldstories/database/index.asp?cid=278

Detail, Kamianets-Podilskyi