At least 863 others were injured. Saudi King Salman said he had ordered a review of Hajj plans after the disaster, in which two large groups of pilgrims arrived together at a crossroads in Mina, a few kilometres east of Makkah, on their way to performing the "stoning of the devil" ritual at Jamarat.
Thursday's disaster was the worst to occur at the pilgrimage since July 1990, when 1,426 pilgrims suffocated in a tunnel near Makkah.
Both incidents occurred on Eid-ul-Azha, Islam's most important feast and the day of the stoning ritual.
Photographs published on the Twitter feed of Saudi civil defence on Thursday showed pilgrims lying on stretchers while emergency workers in high-visibility jackets lifted them into an ambulance.
Other images showed bodies of men in white Hajj garments piled on top of each other. Some corpses bore visible injuries.
Unverified video posted on Twitter showed pilgrims and rescue workers trying to revive some victims.
The Hajj, the world's largest annual gathering of people, has been the scene of numerous deadly stampedes, fires and riots in the past, but their frequency has been greatly reduced in recent years as the government spent billions of dollars upgrading and expanding Hajj infrastructure and crowd control technology.
Safety during Hajj is a politically sensitive issue for the kingdom's ruling Al Saud dynasty, which presents itself internationally as the guardian of orthodox Islam and custodian of its holiest places in Makkah and Medina.
Blame
Iran's Supreme Leader, Ayatollah Ali Khamenei, said the Saudi government should accept responsibility for the crush, in which more than 100 Iranian nationals were reported to have died.
"The Saudi government should accept the responsibility of this sorrowful incident ... Mismanagement and improper actions have caused this catastrophe," Khamenei said in a statement published on his website.
King Salman offered deep condolences.
The Interior Ministry spokesman, Mansour Turki said the investigation would look into what caused an unusual mass of pilgrims to congregate at the location of the disaster.
"The reason for that is not known yet," he told a news conference in Mina.
UN Secretary General Ban Ki-moon and the White House offered condolences.
"The United States expresses its deepest condolences to the families of the hundreds of Hajj pilgrims killed and hundreds more injured in the heartbreaking stampede in Mina, Kingdom of Saudi Arabia," White House spokesman Ned Price said.
Iran's Tasnim and Fars news agencies reported that 125 Iranians were among the dead.
Fars reported that Tehran summoned the Saudi charge d'affaires to lodge an official complaint over the disaster.
South African Acting President Cyril Ramaphosa extended condolences to families of the victims and said his government was awaiting information about his country's pilgrims.
Jamarat
Street 204, where the crush occurred, is one of two main arteries leading through the camp at Mina to Jamarat, the site where pilgrims ritually stone the devil by hurling pebbles at three large pillars.
In 2006, at least 346 pilgrims died in a stampede at Jamarat.
"Work is under way to separate large groups of people and direct pilgrims to alternative routes," the Saudi Civil Defence said on its Twitter account.
It said more than 220 ambulances and 4,000 rescue workers had been sent in to help the injured. Some of the wounded were evacuated by helicopters.
An Arab pilgrim who did not want to give his name said he had hoped to perform the stoning ritual later on Thursday afternoon but was now too frightened to risk doing so.
"I am very tired already and after this I can't go. I will wait for the night and if it not resolved, I will see if maybe somebody else can do it on my behalf," he said.
More than 100,000 police and thousands of video cameras are also deployed to allow groups to be dispersed before they reach dangerous levels of density.
"Please pilgrims do not push one another. Please leave from the exit and don't come back by the same route," an officer kept repeating through a loudspeaker at Jamarat.
Two weeks ago, 110 people died in Makkah's Grand Mosque when a crane working on an expansion project collapsed during a storm and toppled off the roof into the main courtyard, crushing pilgrims underneath.
Makkah mishap timeline
Year | Incident | Casualties |
1975 | Fire from gas cylinder blast burns tents for pilgrims | 200 dead |
1987 | Shia pilgrims, demonstrators clash with Saudi security forces | 402 dead, mostly Iranians, 649 injured |
1989 | Two bombs explode in Makkah | 1 pilgrim dead, 16 others injured |
1990 | Stampede at a tunnel in Makkah | 1,426 dead, mostly Malaysians and Pakistanis |
1994 | Stampede at the stoning of the Devil ritual in Mina | 270 dead, mostly Indonesians |
1997 | Fire guts tents in Mina | 340 dead, 1,500 injured |
1998 | Stampede at Jamarat Bridge | 118 dead, 180 injured |
2001 | Stampede again at Jamarat Bridge | 35 dead |
2004 | Stampede at the stoning of the Devil ritual in Mina | 270 dead |
2006 | Al-Gaza Hotel collapses in Makkah | 76 dead, 64 killed |
| Stampede at the stoning of the Devil ritual in Mina | 345 dead |
2011 | Road mishaps and illness | 13 Afghans dead, 12 injured |
2015 | Crane crash at Makkah's Masjid Al Haram | More than 110 killed, 238 injured |