KYIV, Ukraine (AP) — Ukraine on Wednesday marked the 80th anniversary of the Babi Yar massacre, one of the most infamous mass slaughters of World War II.

Babi Yar, a ravine in the Ukrainian capital, Kyiv, is where nearly 34,000 Jews were killed within 48 hours in 1941 when the city was under Nazi occupation. The killing was carried out by SS troops along with local collaborators.

Ukrainian President Volodymyr Zelenskyy laid flowers at the monument the the victims of the massacre on Wednesday.

“Babi Yar. Two short words that sounds like two short gun shots, but carry long and horrid memories for several generations. Because they know and remember that not two gun shots sounded in Babi Yar, but hundreds, thousands, tens of thousands times more,” Zelenskyy said.

All Ukrainian schools on Wednesday held a lesson dedicated to the 80th anniversary of the tragedy.

“The Nazis in Babi Yar, according to various estimates, executed between 100,000 and 200,000 people. Aside from Jews, those were Ukrainians and Roma, prisoners of war and patients of a psychiatric hospital. ... Someone will hear these two scary words and these scary numbers for the first time,” Zelenskyy said.

Ukraine has started the construction of a Babi Yar memorial complex and a museum at the site of the mass executions and plans to unveil it in 2025-2026.