Israel has begun its annual Holocaust memorial day with the nation's leaders attending a solemn ceremony.

Wednesday night's ceremony at the Yad Vashem memorial begins 24 hours of commemorations. German Nazis and their collaborators killed six million Jews in the Holocaust, wiping out a third of world Jewry.

The annual memorial day is one of the most solemn on Israel's calendar. Restaurants, cafes and places of entertainment are shut down, and radio and TV programming are dedicated almost exclusively to documentaries about the Holocaust, interviews with survivors and somber music.

On Thursday morning, Israel is scheduled to come to a standstill as sirens wail for two minutes. Pedestrians typically stop in their tracks as cars and buses halt, and passengers stand on roads with their heads bowed.