At least 717 people were killed and another 863 were injured in a stampede this morning at a Hajj pilgrimage near the Islamic holy city of Mecca. The incident, which the BBC reports is the deadliest at the Hajj in 25 years, comes just 13 days after a crane collapsed into Mecca’s Grand Mosque, killing 109.

The stampede Thursday morning took place as pilgrims gathered in Mina, about three miles from Mecca, to throw stones at pillars that represent the devil. From the BBC:

The Saudi civil defence directorate said in a statement that the stampede occurred at around 06:00 (09:00 GMT) at the junction of Street 204 and Street 223, as pilgrims walked towards the five-storey structure which surrounds the pillars, known as the Jamarat Bridge.

The incident happened when there was a “sudden increase” in the number of pilgrims heading towards the pillars, the statement said.

This “resulted in a stampede among the pilgrims and the collapse of a large number of them”, it added.

Thousands of rescue workers and hundreds of ambulances have been sent to Mina, according to Saudi officials, who expect the death toll to rise.

“We have a stampede accident in Mina, and civil defense is dealing with it,” Brig. Gen. Mansour al-Turki, an Interior Ministry spokesman, told CNN.