Hundreds of people died during this year’s Hajj pilgrimage in Saudi Arabia as the faithful faced intense high temperatures at Islamic holy sites, officials have said.

Saudi Arabia has not commented on the death toll amid the heat during the pilgrimage, which is required of every able Muslim once in their life, nor has the kingdom outlined any causes for those who died.

Hundreds of people have lined up at the Emergency Complex in Al-Muaisem area in Mecca, trying to get information about missing family members.

One list circulating online suggested at least 550 people died during the five-day Hajj. One medic said that the names listed appeared genuine.

That medic and another official said they believed at least 600 bodies were being stored at the facility. The list offered no cause of death.

Each year, the Hajj draws hundreds of thousands of pilgrims from low-income nations, “many of whom have had little, if any, pre-Hajj health care”, an article in the April edition of the Journal of Infection and Public Health said.

Communicable illnesses can spread among the gathered masses, many of whom saved their entire lives for their trips and can be elderly with pre-existing health conditions, the paper added.

However, the number of dead this year suggests something caused the number of deaths to swell. Already, several countries have said some of their pilgrims died because of intense heat that swept across the holy sites at Mecca, including Jordan and Tunisia.

Temperatures on Tuesday reached 47C in Mecca and the sacred sites in and around the city, according to the Saudi National Centre for Meteorology. Onlookers saw some people faint while trying to perform the symbolic stoning of the devil.

Others, including many Egyptians, lost track of their loved ones in the heat and the crowds. More than 1.83 million Muslims performed the Hajj in 2024, including more than 1.6 million pilgrims from 22 countries, and around 222,000 Saudi citizens and residents, according to the Saudi Hajj authorities.

On Wednesday at the medical complex in Mecca, an Egyptian man collapsed to the ground when he heard the name of mother among the dead. He cried for some time before grabbing his mobile phone and calling a travel agent, shouting: “He left her to die!” The crowd tried to calm the man.

Security appeared tight at the complex, with an official reading out names of the dead and the nationalities, which included people from Algeria, Egypt and India. Those who said they were kin of the dead were allowed inside to identify the deceased.

The kingdom’s ruling Al Saud family maintains a major influence in the Muslim world through its oil wealth and management of Islam’s holiest sites.

Like Saudi monarchs before him, King Salman has taken the title of the Custodian of the Two Holy Mosques, referring to the Grand Mosque in Mecca home to the cube-shaped Kaaba that Muslims pray towards five times a day, and the Prophet’s Mosque in the nearby city of Medina.

Saudi Arabia has spent billions of dollars on crowd control and safety measures for those attending the annual five-day pilgrimage, but the sheer number of participants makes ensuring their safety difficult.

Climate change could make the risk even greater. A 2019 study by experts at the Massachusetts Institute of Technology found that even if the world succeeds in mitigating the worst effects of climate change, the Hajj would be held in temperatures exceeding an “extreme danger threshold” from 2047 to 2052, and from 2079 to 2086.

Islam follows a lunar calendar, so the Hajj falls around 11 days earlier each year. In 2030, the Hajj will occur in April, and over the next several years it will fall in the winter, when temperatures are milder.

A 2015 stampede in Mina during the hajj killed over 2,400 pilgrims, the deadliest incident to ever strike the pilgrimage, an AP count showed.

Saudi Arabia has never acknowledged the full toll of the stampede. A separate crane collapse at Mecca’s Grand Mosque, which preceded the Mina disaster, killed 111 people.

The second-deadliest incident at hajj was a 1990 stampede that killed 1,426 people.