JERUSALEM -- Israel came to a halt to the sound of sirens on Monday morning to commemorate the 6 million Jews killed in the Holocaust on the country's national Holocaust Remembrance Day.

At 10 a.m. (0700 GMT), as the two-minute sirens pierced the air, people across the country stood in solemn silence in honor of the 6 million Jewish victims of the Nazis during World War II.

On streets and highways, traffic stopped as the country virtually came to a standstill. Many drivers stepped out of their vehicles, and pedestrians halted their steps, all standing in silence. In many homes, businesses, and offices people stopped their activity.

The annual ritual marked the beginning of a series of memorial activities on the Holocaust Martyrs' and Heroes' Remembrance Day, an official day to honor the Jews who died at the hands of Nazi Germany and its collaborators in World War II.

The solemn day began on Sunday at nightfall. In the opening ceremony, Holocaust survivors lit torches at Yad Vashem, Israel's official Holocaust memorial, in Jerusalem.

In remarks during the ceremony, Prime Minister Benjamin Netanyahu rejected international calls to stop the war in Gaza, declaring: "If Israel is forced to stand alone, Israel will stand alone."

"I say to the leaders of the world, no amount of pressure, no decision by any international forum, will stop Israel from defending itself," he said.

The solemn day is marked in Israel every year, a week before Memorial Day for Israel's Fallen Soldiers and Independence Day. "Its proximity to Memorial Day and Independence Day serves as a symbolic expression of the Jewish people's historical transition from Holocaust to national revival," according to a statement issued by the Knesset, the Israeli parliament.