Several days of extraordinary heat took a major toll on one of the world’s largest religious gatherings, with hundreds reported dead as part of this year’s Hajj pilgrimage in the desert of Saudi Arabia.

Two unnamed Arab diplomats told the Agence France-Presse news service that 323 people from Egypt alone had died, most because of heat-related illnesses. Egypt has not yet shared an official count, but other countries whose citizens flocked to the holy city of Mecca have been reporting tolls: at least 138 from Indonesia, 41 from Jordan and 35 from Tunisia.