During the annual Hajj pilgrimage in Saudi Arabia, one of the most important events on the Muslim calendar, at least 450 people died under a scorching sun as they prayed at sacred sites around the holy city of Mecca.

Amid maximum temperatures that ranged between 108 Fahrenheit and 120, according to preliminary data, and throngs of people, many passed out and needed medical care. The pilgrims, some who have saved their whole lives for the Hajj, spend days walking and sleeping in tents during their journey to Mecca, the holiest city for Muslims. The Hajj is one of Islam’s five pillars, and all Muslims who are physically and financially able are obliged to embark on the pilgrimage.

Indonesia has so far reported the most deaths, 199, and India reported 98. The countries said at this point that they could not be sure that heat was the cause of all the deaths, though relatives of the missing and dead and tour operators have said the heat was at least a contributing factor.

The number of dead is expected to rise as neither Saudi Arabia nor Egypt, where many pilgrims come from, has released death tolls for their citizens.

This year, more than 1.8 million Muslims traveled to Mecca, 1.6 million of them from outside Saudi Arabia, according to the Saudi General Authority for Statistics.

Many complained that there were not enough cooling stations or water for all the pilgrims, and there were early reports that part of the problem was that many people did not officially register for the pilgrimage, possibly to avoid the steep costs of Hajj package tours.

Other countries reporting death tolls include Jordan, Tunisia and Pakistan.

Jordan’s foreign ministry said 75 pilgrims had died “as a result of the intense heat wave.”

Tunisia’s minister of Religious Affairs, Ibrahim Chaibi, said 49 Tunisians had died. He said that number was expected to rise as the number of pilgrims traveling on tourist visas became more clear, according to Tunisia’s state-run news agency.

One Egyptian tour operator said that because of increasing fees for Hajj package tours, as well as the devaluation of the Egyptian pound, many pilgrims opted for tourist visas, which had burdened the facilities set up in Mecca and the surrounding holy sites.

The New York Times News Service