This year has been particularly deadly, despite attempts by the government of Saudi Arabia to make the pilgrimage safer for the more than 2 million people who make the journey each year.
So why do incidents like this keep happening at the Hajj?
Here are 5 things you need to know.
A 'sudden surge in the crowd' Thursday
Performing the Hajj is one of the five pillars of Islam
, and every Muslim who is physically and financially able is required to make the journey to the holy city of Mecca near Saudi Arabia's west coast at least once in their lives.
The pilgrimage takes place over five days and includes many detailed rituals, including wearing purifying white robes, walking counterclockwise around the Kabaa and the symbolic stoning of evil.
Thursday's stampede happened at this ritual stoning in the tent city of Mina, about 2 miles from Mecca. There, pilgrims throw stones at three walls and pillars called the Jamarat in a re-enactment of when the Prophet Abraham stoned the devil to reject his temptations.
At 9 a.m., there was a "sudden surge in the crowd" heading toward the Jamarat, resulting in overcrowding, a spokesman for the Saudi civil defense agency said in a statement from the Saudi Press Agency.
"A large number fell," the statement said.
Journalist Khaled Al-Maeena told CNN over the phone from Jeddah, Saudi Arabia, that pilgrims rushing to finish could have been the main reason for the stampede: "People like to do the first stoning in the morning," he said.
He added: "People must have fainted because it was very hot and humid down there ... and also there have been many cases of dehydration since yesterday."
The stoning ceremony can be risky
The stoning ceremony in Mina was the scene of stampedes and deaths in the 1980s and 1990s because of a crowded bottleneck area on the way to the pillars.
More recently, in 2004, an early morning stampede killed 251 pilgrims and injured another 244. It lasted 27 minutes before being brought under control.
In 2006, a particularly lethal stampede there killed at least 363 people. That time, pieces of luggage spilled from moving buses in front of the entrances to a bridge, causing people to trip, an Interior Ministry spokesman told The Associated Press in a BBC article.
Professor Fawaz Gerges, chairman of Contemporary Middle East Studies at the London School of Economics, says the stampedes there are caused by pilgrims "pushing and shoving to 'stone the devil,' throwing stones in a very narrow area."
The BBC has described it as the riskiest ritual of the Hajj because of the way worshipers jostle, which can knock weaker pilgrims over.
The deadliest Hajj stampede killed 1,426 people
Other significant incidents, by date:
• 1987: More than 400 people, mainly Iranian Shiite pilgrims, are killed in clashes with Saudi security forces during anti-Western protests in Mecca.
• 1990: 1,426 pilgrims are trampled to death.
• 1994: A stampede near Jamarat Bridge kills 270 pilgrims.
• 1997: A fire in Mina tears through a sprawling, overcrowded tent city, trapping and killing more than 340 pilgrims and injuring 1,500.
• 1998: One hundred eighty people die in a stampede near Mecca at the end of the Hajj.
• 2006: A small hotel in Mecca collapses, killing at least 76 people. The hotel, Luluat Alkheir, is occupied by Asian pilgrims when it collapses.
The Saudis spent $1.2 billion on a bridge for pilgrims
As millions of devotees move in a small area, keeping them safe is a huge logistical puzzle for Saudi authorities.
"The numbers grow and grow and grow," said Hugh Kennedy, a professor of Arabic at the London School of Oriental and African Studies. "When the Hajj was in its early days, the numbers were thousands, perhaps even less than that; now we're talking about 2 million. They all want to do the same thing as those thousands did 1,400 years ago.
"It's not just that there are a lot of people there, it's that they want to be in the same places at certain times," he said.
After the 2004 crush, Saudi authorities put in barriers to improve safety
at the stoning site, according to the BBC.
In 2009, the government erected three massive pillars and completed a $1.2 billion, five-story bridge nearby where pilgrims could toss stones.
The Jamarat Bridge is air-conditioned to keep the temperatures at 19 Celsius (66 Fahrenheit) in a place where temperatures can routinely exceed 37 C (99 F), according to U.S. State Department.
The idea was to give the faithful more room and a better atmosphere, and it worked well for a few years.
Journalist Al-Maeena said: "In the past few years, these kind of stampedes (had not) happened because of the ... highway-like bridges to the places of the stoning."
Professor: Infrastructure needed to stop more crushes
The Hajj is possibly the largest gathering of human beings on the planet, Kennedy said.
"We all know from managing things like football crowds how very, very difficult this is, to (manage big crowds of people)," he added.
How to prevent another stampede is a very delicate question for the Saudis, says Gerges, the London School of Economics professor, adding that disasters reflect very badly on authorities in the birthplace of Islam.
"This is a very sensitive question for the kingdom, because the kingdom wants to come across as the custodian of Mecca and Medina, to provide security and safety."
He says that although the Saudis have been enlarging the space in Mina where pilgrims gather for the stone throwing ritual, the latest tragedy proves they need to go further.
"You need a significant infrastructure in terms of police, support, space. Imagine if you have 2 million people in a relatively small town. Mecca is a small town, in particular the sacred sites of Mecca," he said.
"I hope that the Saudi authorities would take a closer look at what needs to be done. The extra measures, the technology, the crowd control, trying to find ways and means to prevent such catastrophes -- not only because it's the responsibility of the kingdom to provide safety, but because it also reflects politically badly on the authorities in the kingdom."