MECCA, Saudi Arabia — Hundreds of people died during this year’s Hajj pilgrimage in Saudi Arabia as the faithful faced intense high temperatures at Islamic holy sites in the desert kingdom, officials said Wednesday as people tried to claim their loved ones’ bodies.

Saudi Arabia has not commented on the death toll amid the heat during the pilgrimage, required of every able Muslim once in their life, nor offered any causes for those who died. However, hundreds of people had lined up at the Emergency Complex in Al-Muaisem neighborhood in Mecca, trying to get information about their missing family members.

One list circulating online suggested at least 550 people died during the five-day Hajj. A medic who spoke to The Associated Press on condition of anonymity to discuss information not released publicly by the government said that the names listed appeared genuine. That medic and another official who also spoke on condition of anonymity said they believed at least 600 bodies were at the facility.

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Historical Context of Hajj Deaths

Deaths aren’t uncommon at the Hajj, which has drawn at times over 2 million people to Saudi Arabia. There have been stampedes and epidemics through the pilgrimage’s history.

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 preexisting 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 the heat that swept across the holy sites at Mecca, including Jordan and Tunisia.

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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.