More than 700 are dead and about 800 more are injured after a stampede in the tent city of Mina, near Mecca, Saudi Arabia, according to a CNN article.

It is not yet certain exactly what set off the stampede Thursday, but the large crowds of people were a contributor, according to the New York Times.

Causes of the stampede are said to include: pilgrims rushing to complete the rituals, heat, masses of faithful pushing against each other in opposite directions and even confusion among the first-time pilgrims’ annual Islamic pilgrimage to Mecca and Mina.

The stampede happened during the celebration of Islam’s second-biggest holiday, Eid Al-Ahda and during a ritual known as stoning the Devil. Saudi Arabia’s health minister blamed the tragedy on “undisciplined pilgrims” who hadn’t followed instructions.

Over 2 million Muslims perform the Hajj pilgrimage annually. The pilgrimage is one of the five pillars of Islam.

Several other stampedes have happened in past years, but Thursday’s stampede was the largest incident in more than two decades. Thursday’s stampede was the deadliest since 1990.

Collegian International Beat Reporter Megan Fischer can be reached at news@collegian.com or on Twitter @MegFischer04.