Mecca, Saudi Arabia (CNN) -- About 1.8 million Muslims were in the holy city of Mecca on Monday for the first day of Hajj, the annual pilgrimage that every able-bodied Muslim is expected to perform at least once in his or her lifetime.
"I hear you calling O Lord, I hear you calling," pilgrims clad in white called across the Plain of Arafat on Monday morning.
Saudi Arabia's Interior Minister Prince Nayef bin Abdul Aziz, who is overseeing Hajj this year, was quoted in the Saudi Press Agency as saying that the pilgrims this year amounted to the "highest number ever recorded."
An additional 1.6 million local residents are expected, bringing the total anticipated number of pilgrims to more than 3.4 million, the Saudi Press Agency said. The pilgrims have come from a total of 181 countries.
The pilgrimage will last five days.
CNN's Raja Razek and journalist Nima Elbagir contributed to this report.