At least 20 people died and 300 were hurt in Baghdad today after insurgents, including roof-top snipers, ambushed pilgrims gathering in their hundreds of thousands for a sacred Shi'ite festival.
The attacks were in Kadhimiya a northern suburb where a sacred shrine is the focal point of the event.
Heavy security was meant to lower the ever-present danger of sectarian strife at a festival with a bloody history.
Police had set up protected corridors to the shrine and urged people to only use designated routes. But with huge numbers cramming the roads, many tried to find short cuts and got ambushed instead.
A resident in the mainly Sunni neighborhood of Waziriya said Shi'ite militiamen fought for several hours with insurgents on its streets after one such attack.
They then searched his home and surrounding buildings for gunmen who had opened fire from the rooftops, and told him that they had killed two.
Defence Minister General Abdul Qader Jassim said that 30 suspected militants had been arrested, including at least five non-Iraqi Arabs, and 14 police had been wounded in the violence.
Last year, 1,000 people died at the festival in a stampede caused by a false claim that a suicide bombing was about to happen.