BAGHDAD - A car bomb exploded Saturday in a bus station in the Shiite holy city of Karbala, killing at least 56 people, police and hospital officials said.

Iraqis are lined up against a wall as a soldier stands guard in Baghdad. A car bomb slaughtered 40 people near a revered Shiite shrine in Iraq's pilgrimage city of Karbala on Saturday, two months to the day after US-led troops launched a security crackdown in Baghdad. [Agencies]

More than 70 people were also wounded in the attack, according to an official at Al-Hussein Hospital. He spoke on condition of anonymity because he was not authorized to release the information.

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Khalid al-Daami, head of the city's security committee, said women and children were among the dead.

"The explosion was a huge one. It took place in a crowded area, and the number of casualties will increase," al-Daami said.

State television aired footage from the scene, in which rescue workers could be seen evacuating casualties. The charred body of a child laid motionless on a stretcher.

Hundreds of people swarmed around ambulances, crying out and pounding their chests in grief.

The attack occurred about 200 yards from the Imam Hussein shrine, where the grandson of Islam's Prophet Muhammad is buried - one of the most important sites for Shiites.

Witnesses said as many as 15 ambulances rushed to the area, and police were firing guns into the air to disperse crowds and clear roads for emergency vehicles.

Karbala lies 50 miles south of Baghdad, and is the destination of an annual Shiite pilgrimage. Hundreds of Shiite faithful were killed traveling back and forth to the city during this year's pilgrimage, which took place last month.

Separately, a suicide car bomb exploded on a major bridge in downtown Baghdad, killing at least 10 people, police said.

At least 15 people were wounded in the attack, which occurred on the Jadriyah bridge over the Tigris river. The extent of damage to the bridge was not immediately clear.

It was the second attack on a major bridge in Baghdad this week.

On Thursday, a suicide truck bomb collapsed the al-Sarafiyah bridge in northern Baghdad, killing 11 people and sending cars plummeting into the waters below.