September 24, 2015 11:43 AM EDT

More than 700 people were killed in Saudi Arabia Thursday when a stampede took place on the outskirts of Mecca during the Hajj pilgrimage.

The deadly surge occurred in Mina, the Associated Press reports, as pilgrims were making their way to perform a symbolic stoning of the devil by throwing rocks against three stone columns. Along with the 717 people who were killed by the stampede, at least 800 more were injured. It was the deadliest tragedy to strike the annual Muslim pilgrimage in more than 20 years.

Write to Tessa Berenson at tessa.berenson@time.com.

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