*A horrific stampede killed at least 717 pilgrims and injured hundreds more Thursday near the holy city of Mecca in Saudi Arabia, the deadliest tragedy to strike the annual hajj pilgrimage in more than two decades, reports The Associated Press.

The tragedy struck as Muslims around the world marked the start of the Eid al-Adha holiday. According to the Saudi civil defense directorate, at least 863 pilgrims were injured in the crush.

It was the second major disaster during this year’s hajj season, raising questions about the adequacy of measures put in place by Saudi authorities to ensure the safety of the roughly 2 million Muslims taking part. A crane collapse in Mecca nearly two weeks earlier left 111 people dead.

mecca stampede

Thursday’s crush happened in Mina, a large valley about 5 kilometers (3 miles) from Mecca that has been the site of hajj stampedes in years past. Mina is where pilgrims carry out a symbolic stoning of the devil by throwing pebbles against three stone columns. It also houses more than 160,000 tents where pilgrims spend the night during the pilgrimage.

According to the Saudi civil defense directorate, Thursday’s tragedy struck during a morning surge of pilgrims at the intersection of streets 204 and 223 as the faithful were making their way toward a large structure overlooking the columns. The multi-story structure, known as Jamarat Bridge, is designed to ease the pressure of the crowds and prevent pilgrims from being trampled.

Amateur video shared on social media showed a horrific scene, with scores of bodies – the men dressed in the simple terry cloth garments worn during hajj – lying amid crushed wheelchairs and water bottles along the street.

Photos released by the directorate on its official Twitter account showed rescue workers helping the wounded onto stretchers and loading them onto ambulances near some of the tents.

Some 2 million people are taking part in this year’s hajj pilgrimage, which is an obligation of every able-bodied Muslim. The pilgrimage began in earnest Tuesday.