Millions of Muslims from around the world have traveled to Saudi Arabia for the Hajj, a pilgrimage that all able Muslims must make at some point in their lifetime.
The stampede took place when two large groups of pilgrims collided at a crossroads in Mina, a few miles east of Mecca, on their way to performing the "Stoning of the Devil" ritual at Jamarat, Reuters reported.
At least 863 pilgrims were injured in what was the annual event's worst disaster in 25 years.
"There were layers of bodies, maybe three layers," a witness told Reuters. "Some people were alive under the pile of bodies and were trying to climb up but in vain, because their strength failed and they dropped dead.
"I felt helpless not to be able to save people. I saw them dying in front of my eyes."
An Algerian pilgrim told Algeria's al-Shurouk television: "We saw death. People were stepping over the mutilated bodies in front of you, four or five on top of each other."
The stampede "was perhaps because some pilgrims moved without following instructions by the relevant authorities," Saudi Health Minister Khalid al-Falih said in a statement.
Saudi King Salman ordered a review of Hajj plans, al-Falih said an investigation would be conducted rapidly and a final toll of dead and wounded calculated, Reuters reported.
Iran expressed outrage at the deaths of 131 of its nationals. In Tehran, hundreds of demonstrators chanted "Death to the Saudi dynasty."
Iran's President Hassan Rouhani, in New York to attend the UN General Assembly, echoed Supreme Leader Ayatollah Ali Khamenei in blaming Saudi Arabia for the incident.
"I ask the Saudi Arabian government to take responsibility for this catastrophe and fulfill its legal and Islamic duties in this regard," Rouhani said in a statement obtained by Reuters.
Iranian survivors described Saudi's response as "too little, too late," saying rescuers arrived two hours after the incident and started collecting dead bodies first instead of helping the injured.
Saudi Arabia's Interior Ministry spokesman was quoted in Saudi media on Friday as saying the security forces had immediately responded and begun to rescue those who fell in the crush.