BAGHDAD — It started as a dispute at a checkpoint in the southern city of Najaf. It led to a showdown Friday between rival Shiite militias, with mortar rounds lobbed, guns fired and rumors flying that an aide to radical cleric Muqtada Sadr had been assassinated.
Nobody was killed in the incident, which sent ripples of unrest from Najaf to as far as Baghdad's Sadr City, 100 miles to the north, but the rapid escalation of rage underscored the potential for open conflict between two of Iraq's most powerful Shiite forces: Sadr's Al Mahdi militia and the rival Badr Organization. Both militias are tied to political groups that are vying for dominance among Iraq's Shiite majority.
The flare-up came on the weekly Muslim day of rest, which is normally relatively peaceful. But it proved volatile for Iraqis as well as U.S. troops.
Across the country, at least 14 Iraqis died in bombings and mortar attacks. In the most serious incident, a roadside bomb targeting a police patrol in southwest Baghdad killed five officers.
The U.S. military Friday reported the deaths of five American troops, bringing to at least 3,363 the number of U.S. forces killed since the March 2003 invasion, according to the website icasualties.org, which monitors war-related casualties.
The unrest in Najaf began when Sheik Salah Ubaidi, one of Sadr's top aides, was stopped at a police checkpoint. Most police in the city are linked to the Badr Organization, the armed wing of the Supreme Council of the Islamic Revolution in Iraq, or SCIRI, the country's biggest Shiite political party.
At a news conference later, an indignant Ubaidi said the officers had refused to let him pass, even after he showed them his identification papers and explained that he was going to be late for Friday prayers. When they confiscated his ID, Ubaidi said, he angrily drove past the checkpoint, only to be blocked at another one.
"The next checkpoint intercepted me and opened fire in the air as they tried to force me out of the car," he said. "One of the officers yelled at me."
More yelling ensued, tempers flared, and soon Al Mahdi militiamen were on the streets of Najaf, carrying assault rifles and grenade launchers.
In the roughly 90 minutes Ubaidi was detained at the checkpoint, unable to contact family and associates, rumors spread that he had been assassinated.
Later, at least one mortar round crashed near a SCIRI office in Najaf, and gunfire broke out. Shops quickly closed and the streets emptied as residents became fearful of battles between the groups, which have clashed previously.
By 5 p.m., the city was calm and Ubaidi had been released, but the tensions had spread to Sadr City, the huge Shiite neighborhood in northeast Baghdad, where a mortar attack on a SCIRI office injured a guard.
Witnesses said the same building was attacked later by armed men, who left after an official from Sadr's local headquarters spoke to them.
Later, Nassar Rubaie, a spokesman for the Sadrist bloc in Iraq's parliament, accused the police of firing at Ubaidi's vehicle and assaulting him.
Rubaie denied that Al Mahdi militiamen had targeted SCIRI offices in Najaf but acknowledged that unrest in Sadr City was "because they heard the sheik was killed."
Also Friday, a U.S. soldier died in a roadside explosion south of Baghdad. Four others died Thursday: two in western Al Anbar province, and two in separate roadside bombings during patrols in east and west Baghdad. An Iraqi interpreter working with the Army also was killed in the west Baghdad incident, the military said in a statement.
A car bomb and two roadside bombs went off overnight in the northern city of Kirkuk, killing six Iraqis and injuring at least 33, police said.
Two mortar shells fell in a residential area southeast of Baghdad, killing two people, and one Iraqi died when a car bomb exploded outside Hillah, about 60 miles south of the capital.
In Baghdad, police reported finding the bodies of 15 people around the city believed to be victims of sectarian death squads.
U.S. military officials announced that Operation Rat Trap, an offensive targeting Al Qaeda-linked groups in Iraq, had resulted in the deaths of two high-ranking insurgents. The two were killed Tuesday in fighting with U.S. forces north of Baghdad. A statement identified the slain insurgents as Sabah Hilal Shihawi and Abu Ammar Masri.
Friday's military statement identified Masri as a foreign fighter involved in planning attacks and providing support for Al Qaeda in Iraq, the most powerful of the insurgent groups. He is not the same person as Abu Ayyub Masri, the apparent leader of Al Qaeda in Iraq, who remains at large.
U.S.-led forces also said they had detained 16 people suspected of smuggling Iranian-made explosives into Iraq from Iran. The raids took place in Sadr City.
U.S. officials have long accused Iran of making highly lethal roadside bombs, known as explosively formed penetrators, which can pierce even tanks.
Iran denies the accusations.
Times staff writer Susman reported from Baghdad and special correspondent Saad Fakhrildeen from Najaf. Times staff writer Saif Hameed and correspondents in Baghdad, Kirkuk and Babil also contributed to this report.