Updated

More than one million Iraqis marched and beat themselves Thursday in blood-soaked processions through this holy city and other Shiite centers around the country to mourn the seventh century death of their revered martyr, Imam Hussein.

Swept by a thick yellow sandstorm, mass processions choked Karbala's wide streets as more than 8,000 security forces and additional militiamen prevented terrorist attacks that have rocked Ashoura ceremonies over the past two years, killing more than 230 people.

Karbala police chief Brig. Razzaq Abid Ali al-Taei said up to 2 million people either marched in drum banging and flag waving parades or watched as the teeming crowd moved by.

Al-Taei said the ceremony ended with no security violations, except for one rocket launched from an area west of Karbala that fell in a field six miles away.

"No one was hurt and some Iraqi suspects were arrested," he said.

Hundreds of thousands of pilgrims began several days ago descending on Karbala, where Hussein is believed buried, for ceremonies marking Ashoura, the 10th day of Muharram in the Islamic lunar calendar.

The United States military has been using unmanned, unarmed aerial drones to provide an overhead view of processions.

Violence continued elsewhere in Iraq as gunmen assassinated a police lieutenant colonel in the turbulent city of Ramadi, police said.

The U.S. military also said a homicide car bomber attacked a U.S.-Iraqi checkpoint Wednesday about 10 miles from the Syrian border, killing five Iraqis and wounding three people, including a U.S. Marine.

Also Thursday, Iraq's deputy justice minister Busho Ibrahim Ali told The Associated Press that U.S. forces are expected to release about 450 male Iraqi detainees next week but none of the four or five women believed to be in custody.

The kidnappers of American journalist Jill Carroll, who was abducted Jan. 7, have demanded the release of all female detainees or they threatened to kill their captive. No sign has been seen of Carroll since video footage of her pleading for her release appeared Jan. 30 on Al-Jazeera TV.

In Karbala, about 20,000 men wearing white shrouds and waving swords above their heads began marching around 2 a.m. between the gold-domed Imam Hussein shrine and another dedicated to his brother, Abbas, less than a mile away.

Following dawn prayers, about 8,000 people, dressed in black as a sign of mourning and including children as young as 8, marched between the two shrines to the deep beat of bass drums.

Some slapped chains across their backs until their clothes were soaked with blood, while others beat their heads with the flat side of long swords and knives until blood ran freely in a ritual of grief that was banned under ousted dictator Saddam Hussein.

Some sliced their foreheads with the edge of a sword in a practice known as "al-Tatbeer" — meaning "sword" in Arabic — and beat themselves while chanting "Haider, Haider," a name by which Hussein's father, Ali, is known.

"Although it is a sad day, I am very happy because I took part in these head-beating processions," said 10-year-old Haider Abbas Salim, whose face was covered in blood. "Imam Hussein's martyrdom teaches us manhood and that we shouldn't fear anything."

Many Iraqis cooked throughout the night: pilgrims attending the ceremonies are given meals of rice and thick soup laden with meat and chick peas.

Hussein, the grandson of Islam's Prophet Muhammad, was massacred along with about 70 followers by an army of Umayyads, their rivals for leadership of the Muslim community, during a 680 A.D. battle in Karbala. Hussein's death cemented the split in Islam between Shiites and Sunni Muslims.

The ceremonies come amid heightened sectarian tensions in Iraq between Shiites and Sunni Arabs and a campaign of reprisal kidnappings and killings. The U.S. is backing efforts to form a new unity government comprising Iraq's Shiites, Sunni Arabs and Kurds.

Pools of fresh blood covered the road through Karbala. The scene was repeated across the country, including in Baghdad's northern Kazimiyah suburb, a Shiite stronghold. Shiite pilgrims from other countries, including India, traveled to Karbala to attend the ceremony.

Following midday prayers, mourners re-enacted episodes from the massacre of Hussein and his followers, including the burning of his tents. Thousands of people ran several miles through Karbala's streets to the two shrines in a ceremony re-enacting the frantic sprint of the relatives of the massacred, who arrived too late to fight alongside them.

Only 15 percent of the world's 1.5 billion mostly Sunni Muslims are Shiites, but they are the majority in Iraq, comprising about 60 percent of Iraq's 27 million people.

"This is very old tradition which the cursed Saddam denied us for more than 20 years," said Mohammed Karim Hassan, 62, who had streaks of blood across his face after beating the top of his head with a sword. "It is something very small to hit my head and draw blood in grief for Imam Hussein."

Last year, eight suicide bombers killed 55 Shiites in an Ashoura ceremony, while in 2004, at least 181 people were killed in 2004 by twin blasts at Shiite Muslim shrines in Baghdad and Karbala. The Al Qaeda in Iraq group headed by Jordanian-born militant Abu Musab al-Zarqawi claimed responsibility for the attacks.