AT LEAST 31 pilgrims have died and another 100 were wounded in a stampede after a walkway collapsed in Iraq's holy city of Karbala.
Today's death toll - released by the Iraqi Health Ministry - was expected to rise, with at least 10 people in critical condition, said officials.
The deaths occurred toward the end of the Ashura festival procession, during the Shi'ite Muslim religious rituals at the Imam Hussein shrine.
Shrine officials told news agency Reuters the stampede took place at the entrance to the ornate building.
The annual pilgrimage marking the death of the Prophet Mohammed's grandson in battle in 680 draws hundreds of thousands of Shi'ite Muslims to Karbala from around the world.
The rituals commemorating the death involve self-flagellation, with crowds of mourners striking themselves and some lacerating their heads with blades.
Stampedes have occurred in the past.
Associated Press said it was the deadliest stampede in recent history during Ashura commemorations, some 50 miles (80km) south of Baghdad.
There was a panicked rush among worshippers near the gold-domed Imam Hussein shrine as pilgrims saw people being crushed to death.
CHAOS AFTER COLLAPSE
Tuesday's commemorations were peaceful until the walkway collapsed, triggering the chaos.
The incident took place during the so-called "Tweireej" run, when tens of thousands of people run toward the shrine around noon.
The one-two-mile run symbolises when the maternal cousins of Imam Hussein's half-brother al-Abbas ran from the nearby village of Tweireej to rescue him, only to find out that he had been killed.
Images of the ceremonies showed devout Muslims using knives to cut open their heads earlier today, during a traditional show of faith.
The commemorations take place on Ashura, the tenth day of the first month of the Islamic calendar.
They mark Husayn's death at the Battle of Karbala, fought between Husayn and Yazid I on October 10 680AD to determine who should succeed the prophet as the leader of Islam.
Yazid is considered a tyrant by some Muslims, and Husayn's death is considered by the Shia community to be a symbol of humanity's struggle against injustice, tyranny, and oppression.
DRAWING BLOOD
The anniversary is a national holiday in Afghanistan, Iran, Iraq, Lebanon, Bahrain, and Pakistan, and typically involves public expressions of mourning.
Some Muslims mark the day with the practice of Tatbir, in which a sword or scourge is used to draw blood in remembrance of the innocent blood of Husayn.
Many who take part in the practice believe it cleanses them of their sins.
A popular saying among Shia Muslims has it that "a single tear shed for Husayn washes away a hundred sins".
The ritual, which is sometimes carried out on children, is controversial within the Muslim world, with some research suggesting it can cause lasting psychological damage.
Many clerics also consider it to be self harm, which is "haram" - forbidden - in Islam.
Others worry that the practice creates a negative image of their faith.
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Worshippers are instead encouraged to donate blood, with some communities organising donation drives with organisations like the Red Cross.
Other rituals carried on Ashura include mourning processions, recitations of mournful poetry, and services in which the history of the Battle of Karbala is retold.