Sixty-eight Indian nationals were among the 645 persons who died during the Hajj pilgrimage in Saudi Arabia’s Mecca this year, which was marked by soaring temperatures, AFP reported on Wednesday.

“We have confirmed around 68 [Indians] dead [during the pilgrimage],” an unidentified Saudi diplomat told AFP. “Some [deaths] are because of natural causes and we had many old-age pilgrims. And some are due to the weather conditions, that’s what we assume.”

The diplomat also said that a few pilgrims from India were missing, AFP reported. However, he did not provide an exact number. “This happens every year...We can’t say that it is abnormally high this year,” he said.

Temperatures rose to as high as 51.8 degree Celsius in Mecca on Monday, Reuters reported citing a Saudi state-run news agency.

The Hajj pilgrimage is one of the five key obligations of Islam that Muslims with the means to do so are expected to fulfil at least once in their lifetime. The dates of the Hajj are determined by the position of the moon according to the Islamic lunar calendar. The ritual lasts several days and ends in Mecca.

On Tuesday, two other unidentified Saudi diplomats told AFP that 550 deaths were recorded during this year’s Hajj pilgrimage. However, the news agency’s final tally put the number at 645.

Three hundred and twenty-three of them were Egyptians and 60 were from Jordan, the diplomats said. Nearly all the Egyptians died “because of [the] heat”, AFP quoted the diplomats as saying.

Authorities from Indonesia, Iran, Senegal, Tunisia and Iraq’s autonomous Kurdistan region also confirmed that their citizens had died during the pilgrimage, AFP reported. The causes of all the deaths were not specified.

The pilgrimage this year began on June 14 and ended on Wednesday. More than 1.8 million Muslims performed the Hajj this year. This included more than 1.6 million pilgrims from 22 countries.

The Saudi government reported over 2,700 cases of “heat exhaustion” during the day on Sunday.