Hundreds reportedly died at this year's Hajj in Saudi Arabia

Hundreds of pilgrims died during this year’s Hajj, the five-day Islamic pilgrimage to Mecca in Saudi Arabia, local officials revealed on Wednesday.

More than 1.83 million Muslims from 22 countries participated in the pilgrimage this year, according to Saudi Arabia's Hajj authority. The pilgrimage is a mandatory religious duty for all financially and physically able Muslims to complete at least once in their lifetime.

An emergency responder, speaking anonymously, told the Associated Press that estimates of at least 550 deaths were likely accurate.

On Wednesday, hundreds of people reportedly gathered outside the Emergency Complex hospital in the Al-Muaisem neighborhood of Mecca seeking information on missing family members, according to a correspondent at the scene. There was a significant security presence at the hospital when an official read out the names and nationalities of the deceased.

Saudi Arabia reveals no specifics

Saudi officials have not commented on the specific causes of the deaths, but temperatures in Mecca reached 47° Celsius (117° Fahrenheit) on Tuesday, according to the kingdom’s meteorological agency. Earlier this week, the Jordanian Foreign Ministry confirmed that several of its citizens had died due to heat-related causes.

Despite a $5 billion investment by the Saudi government in Hajj-related safety measures, fatalities remain common due to the massive number of participants.