Israel’s largest religious festival turned into its largest peacetime tragedy late Thursday night, as 45 celebrants were crushed to death, and dozens more were injured, under the feet of fellow worshippers in a horrific stampede at Mount Meron.

The annual Lag B’Omer pilgrimage commemorating the teachings of one of Judaism’s greatest mystics, Rabbi Shimon bar Yochai, has been marked for centuries by festive music and bonfires. The bonfires symbolize the great spiritual light that his teachings have brought to the world, as well as the souls’ yearning to connect to their Creator. This year, however, awe-inspiring light turned to unthinkable darkness.

Israeli Prime Minister Benjamin Netanyahu called for a national day of mourning on Sunday, as the last of those killed were laid to rest. Thousands participated on Friday in blood drives for those receiving emergency medical treatment.

And while a majority of pilgrims were members of Israel’s various Orthodox sects, Israelis from all sectors are attempting to expose the causes of a preventable tragedy.