Baghdad: Three car bombs blasted through security checkpoints ringing the Iraqi holy city of Karbala on Thursday and killed at least 51 people, most of whom were Shiite pilgrims headed to observe yearly religious rituals.
It was the latest in a wave of attacks in recent days, as insurgents test Iraqi security forces ahead of the planned US withdrawal at the end of the year.
There was no immediate claim of responsibility, but the bombings bore the hallmark of al-Qaeda and other Sunni-dominated extremist groups that frequently target Shiite pilgrimages in hopes of re-igniting sectarian violence that brought Iraq to the brink of civil war just a few years ago.
Authorities estimated as many as 183 people were wounded in the near-simultaneous blasts set off by three suicide bombers driving cars packed with explosives.
Ali Khamas, a pilgrim from the Shiite neighborhood of Sadr City in Baghdad, said he saw a car speeding toward one of the checkpoints, its driver refusing to stop despite warnings screamed by Iraqi soldiers.
"He sped up and blew up his car near the checkpoint," said Khamas, a 42-year-old truck driver. "After the explosion, people started to run in all directions, while wounded people on the ground were screaming for help. I saw several dead bodies on the ground."
Still, Khamas said, the pilgrims continued to head to Karbala: "It will not deter us from continuing our march to the holy shrine ... even if the explosions increase."
Crowds of pilgrims headed to a Karbala hospital to donate blood for the wounded. Authorities said 11 soldiers and policemen were among the dead, and the rest were pilgrims.
Iraqi security officials and hospital staff who gave details on the attacks and casualty figures all spoke on condition of anonymity because they were not authorized to release information.
The series of attacks this week shattered a relative calm since the formation last month of a new government under Prime Minister Nouri al-Maliki, a Shiite whose family comes from the Karbala area.
The attacks point to the resiliency of the Sunni insurgents and to the inability of the Shiite-dominated security forces to prevent major assaults, even though the level of violence is far lower than at the height of the war three years ago.
As long as Iraq`s security forces are unable to stop such attacks, there is a risk that extremists could re-ignite sectarian violence and destabilize the country as the American military presence fades.
Al-Maliki adviser Adil Barwari said the attacks show extremists` determination "to undermine the new Iraqi government."
He noted that insurgents also likely hope to spook other nations who are sending delegates to the Arab League summit in Baghdad in March — the first time Iraq has hosted the meeting in 20 years.
"They want it to fail," Barwari said. "But al Qaeda will not succeed in achieving this goal."
Pilgrims are headed to Karbala for religious rituals that mark the end of an annual 40-day mourning period observing the seventh-century death of Imam Hussein, the grandson of the Prophet Muhammad. Imam Hussein is one of the most revered figures among Shiite Muslims and was killed in Karbala in a battle that sealed Islam`s historic Sunni-Shiite split.
Attacks against Shiite pilgrims have been a tactic of Sunni extremists since the early years of the Iraq conflict. Shiite politicians encouraged huge turnouts at religious celebrations to dramatize the power of the Shiite majority after the fall of the Sunni-dominated regime of Saddam Hussein.
"The enemies always develop their tactics and improvise new plans to make use of any security breach," said Karbala provincial councilman Shadhan al-Aboudi.
He blamed the blasts on al Qaeda and Saddam loyalists: "They have apparently found a gap today in the security measures and they carried out an evil act against innocent believers who were practicing religious rituals."
The bombings were the latest in a three-day barrage of attacks across Iraq that have killed more than 120 people since Tuesday.
Earlier Thursday, a suicide bomber rammed his explosives-packed car into the front gate of a police headquarters in the eastern Iraqi city of Baqouba, killing three. Another, earlier strike on Shiite pilgrims walking to Karbala from Baghdad killed one and wounded 10 of them.
A day earlier, on Wednesday, another suicide bomber killed seven people after he blew up the ambulance he was driving into a security compound run by guards tasked with protecting government facilities in Baqouba.
And on Tuesday, 65 people died when a suicide bomber set off his explosives-packed vest in a crowd of police recruits in Saddam Hussein`s northern hometown of Tikrit.