About 50 suspects were detained in connection with car bombings that killed at least 65 people and wounded more than 150, Iraqi officials said this morning.
With elections scheduled for the end of Janauary, insurgents have stepped up their attacks against Shiite strongholds such as Najaf and Karbala, both scene of car bombs on Sunday.
Another explosion rocked Karbala this morning. No casualties were reported.
Sunday's attacks were the worst since the end of July. At least 54 people were believed killed in Najaf and more than a dozen in Karbala. Estimates of the wounded ranged from 150 to 200.
In a separate ambush in Baghdad, heavily armed militants attacked a car carrying five employees of Iraq's Independent Electoral Commission, dragging three of the workers out of the vehicle and executing them in the street in front of scores of rush-hour drivers.
Iraqis buried the dead today in processions in the Shiite cities. In Najaf, officials announced they were questioning 50 Iraqis suspects in the bombing. The attacks appeared to be the latest attempt by insurgents to provoke chaos and instability before the Jan. 30 election.
"We blame the extremists, fundamentalists and remnants of the old regime," Mohammed Hussein Hakim, spokesman for and son of one of Najaf's leading Shiite clerics said Sunday. "They are trying to bait a sectarian conflict and create a state of terror among the Iraqi people."
Shiites represent about 60% of Iraq's population and have been among the leading proponents of elections. Led by Grand Ayatollah Ali Sistani, the long-oppressed Shiite community is optimistic that a vote next month will allow it to assume a major role in governing Iraq.
The insurgency is largely made up of Sunni Muslims, who lost privilege after the U.S. invasion toppled Saddam Hussein. They have been threatening to boycott the election.
Election officials vowed Sunday to continue their work.
"We won't be frightened by a few terrorists," said Hussein Hindawi, head of the commission charged with supervising the coming vote. "These inhumane crimes do not represent the Iraqi people."
Sunday's attack in Baghdad brings to nine the number of election workers killed so far, Hindawi said. Two were slain Saturday when a mortar round hit their office in Dujayl, a town about 40 miles north of the capital.
The car bombs in Shiite-dominated southern Iraq struck within two hours of each other Sunday afternoon, both exploding near the cities' gold-domed shrines, which rank among the holiest sites in Islam.
The second and more deadly of Sunday's explosions struck in Najaf. The blast occurred at 3:30 p.m. in a narrow street where dozens of clinics and doctors' offices are located, about 300 yards from the Imam Ali shrine. Among the victims were patients seeking treatment, including numerous women and children, witnesses said.
The city's police chief and the regional governor were attending a funeral procession not far from the blast site, but neither was injured.
"This attack targeted innocent Iraqis," said Adnan Zurfi,Ö governor of the region.
At Zehra Hospital, frantic relatives searched for loved ones among charred, mangled bodies laid out in the hospital garden.
"Why did you leave the house?" one anguished man cried over the body of his brother. "You are newlywed and your bride is waiting for you."
Hospital officials said 49 were killed and 90 wounded in the blast. There were conflicting reports over whether the attacker or attackers were among the dead.
The bombing broke a relative calm in Najaf after battles in August between U.S. troops and followers of radical cleric Muqtada Sadr.
American officials have been leading a $200-million reconstruction program to rebuild the Old City, which was heavily damaged in the summertime fighting and suffered another devastating blow Sunday.
About two hours before the attack in Najaf, a car bomb struck near a bus station in Karbala. Thirteen were killed and 30 injured, officials said. The explosion ignited a row of minibuses and left a 5-foot crater in the asphalt.
Both cities had been targeted before. On Wednesday, a senior Shiite cleric narrowly escaped assassination in Karbala when a bomb exploded as he was traveling to evening prayers at the Imam Hussein shrine, killing at least seven people and wounding dozens. In March, bombers killed about 85 celebrants during a religious gathering in the city.
In August 2003, a car bomb killed revered cleric Ayatollah Mohammed Bakr Hakim and scores of others in Najaf as they left Friday prayers.
The attack on election workers earlier Sunday occurred in the area of Haifa Street, one of Baghdad's oldest and most dangerous neighborhoods. More than 30 militants armed with pistols, machine guns, Kalashnikov assault rifles and hand grenades swarmed the car carrying five election workers before pulling three of the workers into the street, officials said.
An Associated Press photographer captured pictures of the attack, showing one election worker lying on the ground as a gunman aimed a pistol at his head. A second election worker, cowering on his knees nearby, was shot seconds later, AP reported.
The employees were identified as Hatem Ali Hadi Moussawi, a lawyer and deputy director of one of the commission's offices in Baghdad, and two of his office employees, Mahdi Sbeih and Samy Moussa.
The two other workers escaped the attack, though it was not immediately clear how.
Unlike the approximately two dozen election workers assigned to the United Nations, who live and work inside the heavily guarded Green Zone, most of the 6,000 Iraqi employees of the nation's electoral commission travel without weapons or heavy security. Officials fear the workers were followed.
"There was a huge number of terrorists involved," said Hindawi, the commission chief. "We think it was an organized attack."
He said the recent attacks had not resulted in any resignations or large-scale defections from his staff, but there were signs that the increase in violent strikes was taking a toll.
"We are not going to be able to do anything about candidates or voting centers if the security situation stays at this level," said one election worker in the city of Samarra, who was afraid to be identified. He said insurgents had bombed one election center in the city and chased away the supervisor of another with death threats.
Times special correspondents in Najaf and Samarra contributed to this report.