BAGHDAD - A female suicide bomber detonated her explosives inside a way station for Shia pilgrims yesterday, killing 54 people and rattling security officials who are struggling against a possible rise in violence before key elections next month.
The attack was the third major strike by suspected Sunni insurgents in a week and left Baghdad's top security official acknowledging that extremists are adopting new methods to outwit bomb-detection squads such as stashing explosives deep inside the engines and frames of vehicles.
A similar warning about new tactics came last week from the chief U.S. military commander in Iraq, Gen. Raymond Odierno, after a two-day wave of suicide car bombers struck three hotels in Baghdad and the city's main crime lab, killing at least 63 people.
U.S. and Iraqi officials are deeply concerned that insurgents such as al-Qaida in Iraq could step up violence before March 7 parliamentary elections, which are seen as a critical step in reconciliation between the majority Shia and the Sunnis who lost control with the toppling of Saddam Hussein.
Shia pilgrims are easy targets for bombers who can mingle with the crowds streaming on roads to shrines and other sites.
Hundreds of thousands of people are walking this week toward Karbala in southern Iraq before the culmination of religious events Friday, marking the end of 40 days of mourning following the anniversary of the death of Imam Hussein, a revered Shia figure.
Iraqi security forces have promised to protect the pilgrims with expanded patrols and checkpoints. But yesterday's bombing shows the huge challenges of trying to find a single attacker among the throng.
The bomber hid the explosives beneath an abaya, a woman's black cloak worn from head to toe, as she joined a group of pilgrims on the outskirts of the Shia-dominated neighborhood of Shaab, said Maj. Gen. Qassim al-Moussawi, Baghdad's top military spokesman.
The bomber set off the blast, described as a huge fireball, as she lined up with other women to be searched by female security guards at a checkpoint just inside a rest tent serving sherbet and tea.
People were "on the ground, covered in blood and crying for help. Banners were all over the ground and covered in blood," said witness Raheem Kadhom, 35.
The blast was so powerful it blew some people out of their slippers and shoes, which were scattered across the ground, he said. Many of the wounded were loaded into cars instead of waiting for ambulances.
A police official said 54 people, including 18 women and 12 children, were killed and 117 were wounded.