In recent years, Ashoura processions have been attacked by extremist Sunni militants. In 2004, at the height of Iraq’s sectarian violence, 143 people were killed in near simultaneous suicide and other bombings at shrines in Baghdad and Karbala during the Ashoura procession.
In 2005, rumours of a suicide bomber among worshippers crossing a bridge during a different religious holiday caused a massive stampede killing more than 950 people, many of whom jumped, in their panic, into the Tigris River.
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 of Imam Hussein in Karbala around noon.
The 2-3 kilometre 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.
Earlier in the day, hundreds of thousands of black-clad pilgrims held Ashoura processions amid beefed-up security in Karbala and in the capital, Baghdad, marching through the streets. Many of the faithful beat their chests and lashed themselves with chains in a symbolic expression of grief and regret for not being able to help Hussein before his martyrdom.
On Sunday night, thousands marched toward the holy shrine of Imam Hussein in Karbala, which had been lit up on the eve of the celebration.
This year’s commemoration comes amid rising tensions in the Middle East and the crisis between Iran and the US and its ally Israel in the wake of the collapsing nuclear deal between Tehran and world powers.
Israel has recently expanded its war on Iran and its allies in the region, and is believed to have struck targets as far out as Iraq in recent weeks, drawing outrage and pledges of retaliation.