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Millions fill Mecca as the hajj pilgrimage peaks

Fayez Nureldine / AFP - Getty Images

An aerial view shows tens of thousands of tents hosting piligrms in Mina near the holy city of Mecca, on Oct. 16, 2013.

Fayez Nureldine / AFP - Getty Images

Muslim pilgrims head to the "Jamarat" ritual, the symbolic stoning of Satan, where they throw pebbles at pillars, in Mina near the holy city of Mecca, on Oct. 16, 2013.

Amr Nabil / AP

Saudi police officers monitor crowds of pilgrims at holy places in Mina and at the Grand Mosque in Mecca, Saudi Arabia, Oct. 16, 2013. More than 2 million pilgrims - about 1 million fewer than last year - are performing the hajj,

Fayez Nureldine / AFP - Getty Images

Muslim pilgrims head to the "Jamarat" ritual, the symbolic stoning of Satan, where they throw pebbles at pillars, in Mina near the holy city of Mecca, on Oct. 16, 2013. Pilgrims pelt pillars symbolising the devil with pebbles to show their defiance on the third day of the hajj as Muslims worldwide mark the Eid al-Adha or the Feast of the Sacrifice, commemorating Abraham's willingness to sacrifice his son Ismail on God's command.

Amr Nabil / AP

Muslim pilgrims circle the Kaaba as they pray inside the Grand Mosque during the hajj, in Mecca, Saudi Arabia, Oct. 15, 2013. The hajj, a central pillar of Islam and one that able-bodied Muslims must make once in their lives, is a four-day spiritual cleansing based on centuries of interpretation of the traditions of Prophet Muhammad.