Shiite Muslims' holiest day
Iraqi Shiite Muslims repeatedly hit their heads with blades to show their religious devotion.
Iraqi Shiites commemorate the death of the founder of their branch of Islam.
Iraq's Shiite Muslims have fought to get what they want in the new interim constitution.
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(CNN) -- It is the holiest day for Iraq's Shiite Muslims.
Tens of thousands of people -- perhaps even more than a million -- have descended on the great mosques of Karbala in Iraq for this year's Ashura commemoration.
Ashura commemorates the martyrdom of Imam Hussein -- a top Shiite saint and the grandson of the prophet Muhammad -- who died in 680.
Banned under Saddam Hussein's Sunni-dominated regime for fears it could foment rebellion, the event this year held special significance because it was the first time in 30 years Shiites were allowed to observe it.
Massive crowds of men, women and children from Iraq, Iran, Pakistan and other parts of the world traveled to Karbala for the most important observance in the Shiite Muslim calendar.
But the prayers and other elaborate religious rituals on Tuesday in Karbala were literally blown away as blasts and mortar shell attacks ripped through the outskirts of the city.
The attacks came despite authorities being on high alert. Polish soldiers had been patrolling entry points to the city and Shiite militants guarded streets and shrines.
The city center had also been sealed for fear disgruntled Sunni militants might target the celebrations amid a growing dominance of Shiite Muslims in post-Saddam Iraq.
It seems those security efforts were in vain.
In the immediate aftermath of the blasts and as casualties were still being counted and treated, worshippers voiced their anger at how such a religious day could be targeted.
But many refused to vacate the streets, determined to fulfill their religious ceremonies despite efforts by security forces to clear the area.
Shortly after the explosions, pilgrims returned to the Imam Hussein mosque: chanting, beating their breasts in penance, cutting themselves with daggers or swords and whipping themselves in synchronized moves.
Thousands offer afternoon prayers at the Imam Hussein holy shrine in Karbala on Monday.
The dramatic and passionate re-enactments of a turning point in Islamic history have deep relevance for Shiite believers in Iraq.
It was in Karbala over 1300 years ago that Imam Hussein was slaughtered in a hopelessly one-sided battle after a failed uprising to defeat the tyrannical rule of a powerful Sunni.
More recently, the ousted Iraqi regime was run by a Saddam Hussein, a Sunni despot who ruthlessly oppressed the Shiite majority -- a situation that resonated, many Shiites say, with Imam Hussein's own struggle.
Now, their religious and political leadership has re-surfaced and they are becoming the most influential group in post-Saddam Iraq.
As the 10-day observation neared its peak, men wept publicly at the gates of Imam Hussein's temple.
But on Tuesday tears for the martyr were joined by tears for the dead and injured from that day's multiple explosions.
CNN's Brent Sadler contributed to this report