Muslim pilgrims make their way to cast stones at a pillar in the "stoning the devil" ritual Thursday, September 24, in Mina near Mecca, Saudi Arabia. At some point during this last rite of the annual Hajj, <a href="http://www.cnn.com/2015/09/24/world/gallery/saudi-arabia-stampede/index.html">a stampede occurred, killing and injuring hundreds</a>. More than 2 million Muslims have been making the pilgrimage to the holy city of Mecca. The Hajj is one of the most celebrated events in the Islamic calendar.
Muslim pilgrims make their way to cast stones at a pillar in the "stoning the devil" ritual Thursday, September 24, in Mina near Mecca, Saudi Arabia. At some point during this last rite of the annual Hajj, a stampede occurred, killing and injuring hundreds. More than 2 million Muslims have been making the pilgrimage to the holy city of Mecca. The Hajj is one of the most celebrated events in the Islamic calendar.
Mosa'ab Elshamy/AP
A pilgrim reads the Quran on a rocky hill called the Mountain of Mercy, on the plain of Arafat, near Mecca on Wednesday, September 23.
A pilgrim reads the Quran on a rocky hill called the Mountain of Mercy, on the plain of Arafat, near Mecca on Wednesday, September 23.
Mosa'ab Elshamy/AP
Muslim pilgrims pray at Namira Mosque on September 23 on Mount Arafat near Mecca.
Muslim pilgrims pray at Namira Mosque on September 23 on Mount Arafat near Mecca.
MOHAMMED AL-SHAIKH/AFP/Getty Images
Pilgrims join in one of the Hajj rituals early September 23 on Mount Arafat. For most Muslims, the pilgrimage is the spiritual climax of their lives, with many saving for decades to be able to make the journey to Mecca.
Pilgrims join in one of the Hajj rituals early September 23 on Mount Arafat. For most Muslims, the pilgrimage is the spiritual climax of their lives, with many saving for decades to be able to make the journey to Mecca.
MOHAMMED AL-SHAIKH/AFP/AFP/Getty Images
Muslim pilgrims pray on the Mountain of Mercy, on the plain of Arafat. Islam requires every Muslim who is physically and financially able to make the journey to Mecca at least once in his or her lifetime.
Muslim pilgrims pray on the Mountain of Mercy, on the plain of Arafat. Islam requires every Muslim who is physically and financially able to make the journey to Mecca at least once in his or her lifetime.
Mosa'ab Elshamy/AP
Muslim pilgrims pray on the Mountain of Mercy on Tuesday, September 22.
Muslim pilgrims pray on the Mountain of Mercy on Tuesday, September 22.
Mosa'ab Elshamy/AP
Muslim pilgrims touch Islam's holiest shrine, the <a href="https://www.khanacademy.org/humanities/art-islam/beginners-guide-islamic/a/the-kaaba" target="_blank" target="_blank">Kaaba</a>, at the Grand Mosque in Mecca on Monday, September 21. Performing the Hajj is one of the five pillars of Islam.
Muslim pilgrims touch Islam's holiest shrine, the Kaaba, at the Grand Mosque in Mecca on Monday, September 21. Performing the Hajj is one of the five pillars of Islam.
MOHAMMED AL-SHAIKH/AFP/AFP/Getty Images
Muslim pilgrims circle counterclockwise the Kaaba at the Grand Mosque in Mecca on Monday. The pilgrimage, conducted over five days, includes detailed rituals including wearing a special garment that symbolizes human equality and unity before God, a procession around the Kaaba and the symbolic stoning of evil.
Muslim pilgrims circle counterclockwise the Kaaba at the Grand Mosque in Mecca on Monday. The pilgrimage, conducted over five days, includes detailed rituals including wearing a special garment that symbolizes human equality and unity before God, a procession around the Kaaba and the symbolic stoning of evil.
Mohammed Al-Shaikh/AFP/Getty Images