Mina, Asharq Al-Awsat—The Hajj tragedy that has left hundreds of people dead and injured was caused by a group of Iranian pilgrims who failed to follow instructions from Hajj authorities, an official from Iran’s Hajj mission has revealed.

At least 717 pilgrims were killed and 863 injured on Thursday when two large groups of people collided at a crossroads in Mina, east of the Muslim holy city of Mecca, the Saudi interior ministry said.

The official, who requested anonymity to discuss the issue, said the accident occurred after a group of around 300 Iranian pilgrims failed to follow orders requiring them to wait for clearance to leave Jamarat—the site where pilgrims perform the “stoning the devil” ritual.

Instead, the group went back to their mission’s headquarters as other groups were on their way to the site as scheduled, according to the official.

“The group stopped for a while, causing the coming pilgrims to take a route no more than 20 meters wide,” he said, adding that such behavior often leads to tragic consequences in crowded areas.

The Iranian pilgrims were scheduled to leave Jamarat hours after the accident took place, the official said.

Meanwhile, a Saudi security source said authorities may check security cameras installed in the tunnel leading to Jamarat to verify when the Iranian group left the site.

Saudi Arabia’s King Salman Bin Abdulaziz on Thursday offered his condolences to the families of the victims and promised that “the improvement of the methods and mechanisms of the Hajj season will not stop.”

The majority of eyewitnesses who spoke to Asharq Al-Awsat agreed that the crush occurred after pilgrims “failed to follow orders from security.”

Yahia Hamida, a 26-year-old pilgrim from Jordan, told Asharq Al-Awsat that “an unusual mass of pilgrims congregated on Street 204 [that leads to Jamarat] after some entered the wrong lane.”

“Movement on Street 204 was normal until a large number of pilgrims came in the opposite direction, which stopped movement for about an hour and a half before the elderly began to collapse,” another pilgrim said.

Saudi interior ministry has said investigations into the causes of the tragic stampede were underway and that “high temperature and tiredness” contributed to the accident.

Ibrahim Al-Qurashi contributed additional reporting from Mina