Twin car bombs targeted a meeting of U.S.-allied Sunni tribal leaders Monday in Baghdad, killing at least 14 people civilians and wounding 45, a military spokesman said.

A dense cloud of black smoke filled the air as firefighters hosed down dozens of charred vehicles, with flames shooting out of the back of one pickup truck.

The attack occurred near the heavily fortified offices of Abdul-Aziz al-Hakim, the leader of the country's largest Shiite party, the Supreme Islamic Iraqi Council, or SIIC, but the chief military spokesman for Baghdad said the apparent target was a nearby building in which Sunni chieftains from Anbar province who have joined forces against Al Qaeda in Iraq were meeting.

The spokesman, Brig. Gen. Qassim al-Moussawi, said an explosives-laden minibus and a sedan blew up nearly simultaneously — the first near a gas station and the second within minutes near the tribal chiefs meeting, al-Moussawi was quoted as saying by a spokesman.

He said 14 people were killed, 45 wounded and 15 cars were set ablaze, but he could not immediately provide a breakdown of casualties in each blast.

Iraqi police, who spoke on condition of anonymity because they weren't authorized to release the information, said at least three members of the Anbar awakening movement were wounded. The Anbar sheiks often meet in Baghdad and have been lobbying the national parliament in recent days over stalled draft legislation that would set a date for provincial elections.

The blasts ripped a crater two meters (yards) wide in the asphalt. Television footage showed a soldier and a civilian being led away from the scene, pressing cloths to their bloodied heads as sirens wailed around them.

The Americans' new Sunni allies have increasingly been targeted by Al Qaeda in Iraq as it seeks to derail the so-called awakening movement that began in Anbar and has since spread to Baghdad and surrounding areas.

The U.S. military says cooperation from its new Sunni allies and an influx of some 30,000 extra American troops have Al Qaeda on the run, but it has been unable to stop the group's trademark bombings and homicide attacks.

South of the capital, U.S. soldiers captured a suspected Shiite militia commander and one other suspect Monday in the latest of several days of raids in Shiite holy cities.

The suspect was believed to be in charge of criminal operations for so-called rogue militia groups in the Iraqi provinces of Wasit, Babil and Najaf, the military said. He was allegedly involved in coordinating weapons shipments and planning attacks on U.S. and Iraqi forces, the statement said without characterizing the second suspect.

Sadrist lawmaker Ahmed al-Masaoudi, however, told The Associated Press that the two men arrested in Hillah, about 95 kilometers (60 miles) south of Baghdad, were one of his guards and his brother, and he demanded their immediate release.

The military accuses the groups of ignoring Muqtada al-Sadr's cease-fire order and has persisted in raids against them, raising tensions among followers of the radical Shiite cleric.

Al-Sadr's six-month cease-fire is due to expire later this month, and the U.S. has been careful not to accuse the cleric himself of any role in ongoing attacks.

The U.S. military also said soldiers acting on tips had seized 18 armor-piercing explosively formed penetrators, or EFPs, and other munitions in caches found over the weekend in Jurf Nada, a mainly Shiite region southeast of Baghdad over the weekend.

Washington accuses Iran of manufacturing and funneling the EFPs to Shiite militias in Iraq, although Tehran denies the allegations.

The arrests and violence came a day after car bombs and gunmen struck new U.S. allies, police and civilians in northern Iraq, killing as many as 53 people in a spasm of violence that coincided with a visit by U.S. Defense Secretary Robert Gates to Iraq.

Gates on Monday offered his first endorsement for the idea of pausing the drawdown of U.S. forces from Iraq this summer, which some fear could result in giving up some of the security gains of recent months.

The deadliest of Sunday's attacks was near Balad, where Iraqi police and hospital officials said a homicide trucker killed 34 people near a checkpoint manned jointly by Iraqi police and U.S.-backed security volunteers. The American military, however, put the death toll at 23.

New details also emerged about a homicide car bombing at a checkpoint Sunday near the Anbar city of Fallujah, 65 kilometers (40 miles) west of Baghdad.

Police said the two people in the car, a driver who appeared to be a foreigner and a woman wearing a veil, claimed they were working for a British media agency and wanted to interview the head of the anti-Al Qaeda group in the city.

The driver blew himself up when he was ordered out of the car to be searched, killing himself and the woman along with three policemen, according to police.

Also Monday, the U.S. military announced the death of an American soldier, killed in a roadside bombing a day earlier. At least 3,960 American troops have died in Iraq since the war started in March 2003, according to an Associated Press count.

In another development, more than 3,000 people rallied in Baqouba, northeast of Baghdad, the latest in a series of demonstration by U.S.-allied Sunni tribesmen in the city calling for the provincial police chief's resignation and accusing him of sectarian bias.

The fighters — who patrol their neighborhoods on temporary security contracts paid by the U.S. — have grown frustrated with the province's Shiite-dominated government in recent months, and have threatened to halt cooperation.