,BAGHDAD -- Suicide bombers, including at least three women, struck Shiite pilgrims in Baghdad and Kurdish protesters in the northern city of Kirkuk on Monday, killing at least 57 people -- a brutal reminder that mass gatherings remain vulnerable despite vast improvements in security.
The attacks came even though the U.S. has stepped up efforts to recruit and train women for Iraq's police force and enlist them to join Sunnis fighting al-Qaida. Insurgents increasingly use female bombers because their billowing, black robes easily hide explosives and they are less likely to be searched.
U.S. military figures show at least 27 female suicide bombings this year, compared with eight in 2007.
Monday's attacks tapped into two different sets of fears.
The three nearly simultaneous bombings in Baghdad undermined public confidence in recent security gains that have tamped down sectarian bloodshed. The attack in Kirkuk, 180 miles to the north, showed that ethnic rivalries can turn into mass slaughter in a city that is home to Kurds, Turkomen, Arabs and other minorities.
The U.S. military blamed al-Qaida in Iraq for the Baghdad bombings. It was still investigating the Kirkuk attack, underscoring the more complicated nature of the tensions there. But city police spokseman Brig. Gen. Sarhat Qadir said the terror network was behind that attack as well.
The Baghdad bombings left piles of rubble and shattered glass on the streets alongside crumpled cars and sandals from panicked pilgrims, many of whom had slept at rest areas before rising at dawn to begin their annual march to the golden domed shrine of Imam Moussa al-Kadhim.
Hospital emergency rooms were overwhelmed with bloodied victims, including a young boy with a bandaged head who sucked on a pacifier as he was held by a man.
"I heard women and children crying and shouting and I saw burned women as dead bodies lied in pools of blood on the street," Mustapha Abdullah, a 32-year-old man who was injured in the stomach and legs, said from his hospital bed.
At least 32 people were killed and more than 100 were wounded, Iraqi police and hospital officials said. It was the deadliest attack in the capital since June 17, when a truck bombing killed 63 people in Hurriyah.
In a throwback to more violent times, the Iraqi government announced a 24-hour curfew in Baghdad, banning all vehicle movement starting 5 a.m. Tuesday.
The attacks in the capital began about 7:15 a.m., when three of the women detonated their explosives belts in quick succession less than half a mile apart.
The bombers were walking among pilgrims streaming toward the golden domed shrine of the eight-century imam. The shrine, the focus of a major Shiite festival this week, gives its name to the northern neighborhood of Kazimiyah which surrounds it.
Iraqi security forces had deployed about 200 women this week to search female pilgrims in Kazimiyah, but the attacks took place along the procession some six miles southeast of the shrine. There were too few women guards to search people in the procession itself.
The blasts started with an explosion near the National Theater in the central Shiite neighborhood of Karradah, followed by a bombing near a refreshment tent set up for the pilgrims and another between two traffic checkpoints.
Shiites en route to Kazimiyah have been attacked in past years by gunmen in Sunni areas south of Baghdad. No major bombings have struck the pilgrimage, although at least 1,000 pilgrims were killed in a Baghdad bridge stampede caused by rumors of a suicide bomber in 2005.
Since the 2003 ouster of Saddam Hussein, who was a Sunni, Shiite political parties have encouraged huge turnouts at religious festivals to display the majority sect's power in Iraq. Sunni religious extremists have often targeted the gatherings to foment sectarian war, but that has not stopped the Shiites.
Even so, Iraqi authorities had been hopeful they could maintain calm this year as the overall levels of attacks have dropped to their lowest point in more than four years.