Seventy-five years ago Thursday the slaughter of 33,771 Jews began in a valley near Nazi-occupied Kiev.
The mass executions of men, women and children at Babi Yar took place over a 48-hour period between September 29-30, 1941.
They were ordered to strip, marched to the ravine and machine-gunned.
It was one of the most grim atrocities of the 20th century and an early example of how Nazi Germany learned how to commit murder on an unprecedented scale.
Ukraine is marking the anniversary with a weeklong memorial attended by delegations from the United States and Israel including President Reuven Rivlin.
Rivlin, who cut short his trip to attend the funeral of Israeli statesman Shimon Peres, addressed Ukraine's parliament on Tuesday.
"The blood of our brothers and sisters, that was spilled at that dark time, places upon us the duty to remember, and teach the whole world, about the dangers of not just anti-semitism, but of all hatred, and all racism. While we mourn the past, we must also speak about the present, and look to the future," he said.
Ukrainians, Romani and other non-Jewish groups were also killed at Babi Yar at the hands of Nazis with the help of Ukrainian collaborators.
"While Babi Yar was organized by the Nazis, there were willing helpers in the Ukrainian militia," said World Jewish Congress President Ronald S. Lauder. "This happened all across Europe. In almost every occupied country, local people helped the Germans round up their Jews. In some cases, the locals were even more enthusiastic in their killing than the Nazis. And that is what happened at Babi Yar."
