Decades after the Holocaust, stark memories of a German concentration camp creep back to 83-year-old Dirk van Leenan, who spent the week leading up to Saturday's International Holocaust Remembrance Day educating Arizona students on the atrocity.

"I have nightmares about it sometimes," van Leenen said about the Bergen-Belsen concentration camp where he and his family were sent when he was 5 in an interview with The Arizona Republic, part of the USA TODAY Network.

Saturday marked the 79th anniversary of the day Soviet troops liberated Auschwitz, the concentration camp complex where over 1 million people were murdered by Nazis between 1940 and 1945, the vast majority of them Jews. Altogether, Nazis killed 6 million European Jews during the Holocaust.

Since Jan. 27 was designated International Holocaust Remembrance Day in 2005 by the United Nations, the day has drawn survivors and their communities together across the U.S. to remember the lives lost and remind of the importance of combating antisemitism.

"It's important that when we say never forget, that we never forget, and part of that is showing up and listening to the voices of those who experienced the Holocaust and their families," said Massachusetts state Sen. Robyn Kennedy at an event commemorating the Warsaw ghetto uprising on Friday.

The 2024 remembrance events come over three months after about 1,200 Israeli civilians were killed, and over 200 taken hostage, by the militant group Hamas on Oct. 7, 2023, widely regarded as the deadliest day for Jewish people since the Holocaust. The U.S. and nations around the world have recorded an uptick in reports of antisemitism since then. The war has also claimed the lives of over 26,000 Palestinians, Gaza officials have said.

Mary Jane Rein, executive director of Clark University's Strassler Center for Holocaust and Genocide Studies, said at a Friday event commemorating the 1943 Warsaw ghetto uprising in Worcester, Massachusetts, that "violence and murderous attacks against Jews were on the rise long before Oct. 7."

Latest in Israel-Hamas war:Order for Israel to avert genocide in Gaza isn't enforceable. What does it mean?

"On this somber International Holocaust Remembrance Day, we hold the Jewish community and the people of Israel close in our hearts," President Joe Biden said in a statement.

Arizona Holocaust survivor educates students to mark remembrance day

All week, van Leenen recounted surviving a Nazi concentration camp to a room full of Phoenix-area children in an effort to teach young people about the dangers of antisemitism.

Dirk van Leneen is one of approximately 38,400 living Holocaust survivors in the U.S., according to a study published Tuesday by the Conference on Jewish Material Claims Against Germany. Some 65 Holocaust survivors currently reside in metro Phoenix, including some older than 100, according to the Phoenix Holocaust Association’s records.

Van Leneen's father was part of the resistance in the Netherlands, which van Leenen says saved more than 1,000 Jews who were relocated to different parts of the country and placed in hiding. Van Leenen was 5 years old when he and his family were sent in 1945 to Bergen-Belsen – the same German concentration camp where a 16-year-old Anne Frank died of typhus earlier that same year. Two days after they arrived, the camp was liberated April 15, 1945, by the British army.

As Arizona attempts to improve the education of students about the Holocaust, van Leenen told students about the harshness of witnessing camp prisoners die from starvation, falling into “heaps of dead bodies” with their lifeless faces visible. Read more here.

People around the world decry antisemitism Saturday

At the site of the Auschwitz camp, a group of about 20 survivors of various death camps are set to gather Saturday, lay wreaths and say prayers to memorialize the lives lost.

According to the museum that now stands there, the theme of the 79th anniversary is the human being, "symbolically visualised by the faces of the people imprisoned at Auschwitz, immortalised in drawings made during the existence of the camp and after the war."

World leaders in Germany, Ukraine, Italy and elsewhere gave speeches in remembrance. German Chancellor Olaf Scholz said that his country would continue to carry the responsibility for this “crime against humanity.”

"'Never again' is every day,” Scholz said in his weekly video podcast. “Jan. 27 calls out to us: Stay visible! Stay audible! Against antisemitism, against racism, against misanthropy – and for our democracy.”

A memorial ceremony in Warsaw at the foot of the Monument to the Heroes of the Ghetto who fell fighting Nazis in 1943 was held Friday. Earlier in the week, the countries of the former Yugoslavia signed an agreement to renovate Block 117 in the Auschwitz camp and install a permanent exhibition there in memory of about 20,000 people who were deported from their territories and brought to the block.

In the U.S., libraries planned commemorative events with testimonies about local connections to the Holocaust. In Columbus, Ohio, Kehilat Sukkat Shalom and First Unitarian Community Church planned an evening of works including several by composers and writers who perished in or survived the Holocaust.

Family members of Holocaust survivors lit candles, one for every million Jews killed in the Holocaust, at the foot of a memorial at Civic Park in Palm Desert, California, on Friday. Holocaust survivors Rickie Taras and Henry Friedman both attended. Friedman's family hid from Nazis in what was then Brody, Poland, in a barn for 18 months until the area was freed from Nazi control and they were freed.

Contributing: Veer Mudambi, the Worcester Telegram & Gazette; The Palm Springs Desert Sun; The Associated Press