JERUSALEM - Israel observed a national day of mourning on Sunday for 45 people who were killed in a stampede disaster at Mount Meron on Thursday night.

Flags were lowered to half-mast across Israel and the country's diplomatic missions abroad, and cultural and sports events were canceled.

The incident was described as one of Israel's worst civilian disasters since the founding of the country in 1948.

Besides at least 13 children and teenagers aged under 18, the 45 ultra-Orthodox victims also include six US citizens, an Argentinian and a Canadian.

Calls to appoint an investigation committee chaired by a judge have increased on Sunday amid anger towards authorities for overlooking repeated warnings by experts of possible overcrowding.

Also on Sunday, a group of retired police chiefs and commissioners issued a letter to Prime Minister Benjamin Netanyahu, urging him to launch a national committee with wide-ranging authority to investigate.

Tens of thousands of people gathered on Thursday for a traditional festival to mark the Jewish holiday of Lag BaOmer. The stampede is believed to start when people moved through a narrow passageway with slippery metal flooring.