MINA, Saudi Arabia — At least 453 people were killed and hundreds more injured in a stampede today on the outskirts of Mecca, the deadliest tragedy to strike the annual hajj pilgrimage in more than two decades.

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 more than 100 people dead.

Today’s crush happened in Mina, a large valley about three miles from the holy city of 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.

The stampede occurred in 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, according to the Saudi civil defense directorate.

The multi-story structure, known as Jamarat Bridge, is designed to ease the pressure of the crowds and prevent pilgrims from being trampled.

The civil defense directorate, which provided the death toll, said at least 719 other pilgrims were injured in the stampede.