Shiite pilgrims make their way to Iraqi holy city amid tight security

Iraqi police and firefighters inspect the scene following an explosion in Karbala on September 25, 2011.

STORY HIGHLIGHTS

• NEW: Shiites vow to make pilgrimage "even if they terrorists bomb us and kill us"
• Thousands of Shiite pilgrims are making their way to Karbala to mark Arbaeen
• Scores of pilgrims have been killed in attacks blamed on Sunni extremists
• Iraqi security forces have sealed roads around the holy city of Karbala

Baghdad, Iraq -- Iraqi forces have tightened security in and around the southern holy city of Karbala as tens of thousands of Shiite pilgrims pour in ahead of this weekend's culmination of a revered mourning period.

Scores of pilgrims -- who make the journey of foot -- have been killed and wounded in recent days in attacks that have been blamed on Sunni extremists, who have routinely targeted the pilgrims.

The attacks coincide with a political deadlock that has the government divided along sectarian lines that is raising fears, in the wake of the U.S. military's withdrawal from Iraq, of a return to the sectarian bloodshed that nearly tore the country apart during the height of the war.

Prime Minister Nuri al-Maliki ordered security tightened following the attacks on pilgrims. Security forces have sealed roads and increased the number of checkpoints on the main roads leading into the holy city, a three-day walk south for pilgrims making their way from Baghdad.

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The pilgrimage, known as Arbaeen, marks the end of a 40-day mourning period that marks the seventh century death of Imam Hussein, the grandson of Prophet Mohammed.

Hussein was killed during a battle near Karbala for control of the Muslim nation following Mohammed's death in 632. Hussein's death led to a split between Sunni and Shiite Muslims.

During Saddam Hussein's rule, the Sunni leader forbade pilgrims from making the journey on foot. He also banned some ritualistic practices.

Following the U.S.-led invasion that toppled Saddam, the pilgrimages grew in numbers.

This year's pilgrimage comes just weeks after the U.S. military pulled its troops from the country ahead of an end-of-the-year deadline to withdraw.

"We are used to bombings. It is normal for us to face that in our daily life," said Said Duraid Mohammed, a pilgrim. "And for the pilgrimage and Imam Hussein, we are ready to step on the bombs."

Another pilgrim, who identified himself as Mohammed, said he was going to Karbala in spite of the danger.

"We are going to mourn Imam Hussein, even if the terrorists bomb us and kill us," he said. "We are still going."

At least 12 people were killed and more than 50 wounded Monday in car bomb attacks on two predominantly Shiite communities in Baghdad.

On January 5, a suicide bomber struck an army checkpoint in the southern city of Nasiriya where pilgrims were gathered, an attack that killed at least 44 people and wounded 70 others.