BAGHDAD, Iraq (AP) _ Gunmen attacked a minibus carrying Shiites northeast of Baghdad, killing six men and wounding a woman, an official said Saturday. U.S. and Iraqi troops killed three suspected insurgents, and six people were gunned down in the Iraqi capital.

The Shiites were returning home from visiting relatives when they were ambushed Friday night near Balad Ruz, 45 miles northeast of Baghdad, said the town's mayor, Mohammed Maarouf.

The motive for the attack was unclear. However, it occurred in a religiously mixed province where Shiite and Sunni Arabs have carried out numerous acts of violence against each other.

Tension between the rival Shiite and Sunni Muslim communities escalated following the Feb. 22 bombing of a Shiite shrine in Samarra and reprisal attacks on Sunni mosques in Baghdad, Basra and other mixed cities.

In the Iraqi capital Saturday, gunmen killed three ice cream vendors in the southern neighborhood of Dora and a butcher and his son in east Baghdad. Another son of the butcher was wounded. The owner of an air conditioner repair shop was shot and killed on his way to work in the western Iskan neighborhood.

Police discovered two more bodies of young men shot in the head and wearing handcuffs in Baghdad. Witnesses also told police they saw three gunmen in a BMW pull a handcuffed man out of the car and shoot him near a highway in west Baghdad.

Since the beginning of the month, nearly 400 bodies have been found in Baghdad, apparent victims of tit-for-tat killings by Shiite and Sunni extremists.

Also in the capital, a woman and her child were wounded when a mortar shell landed on their house, and a roadside bomb targeted a police patrol, wounding two policemen and three civilians, police said.

U.S. and Iraqi troops killed three suspected insurgents, including a woman in an operation in Amiriyah in Anbar province, west of Baghdad, the U.S. military said. The other suspects were captured.

In Basra, Iraq's second-largest city, a joint British-Iraqi force detained 14 people, including a policeman, in a dawn raid in two neighborhoods, Brig. Patrick Marion said. Four were later released, Marion said.

U.S. officials have been pressing Iraqis to form a government of national unity capable of winning the trust of all communities and cooling the violence.

Representatives of the major Sunni, Shiite and Kurdish parties Iraqi were to meet again Saturday to discuss how much power the prime minister should wield over security forces in the next government.

While March was a bloody month for Iraqi civilians, the death toll for American military personnel stood at at least 29 _ the lowest monthly total since February 2004, according to a count by the Web site icasualties.org.

Communal violence may have been partly responsible for the sharp decline in deaths among American forces as mostly Sunni insurgents shifted their attacks to fellow Iraqis. A total of 117 U.S. service members died in Iraq in the first two months of this year.

In a teleconference with Pentagon reporters Friday, the commander of coalition forces in Baghdad, Maj. Gen. J.D. Thurman, said U.S. losses were also down because Iraqi troops were increasingly taking the lead in the fight against the insurgents.

Giving Iraqi forces a greater role in security is a major U.S. goal so that the Bush administration can begin drawing down its 133,000-strong military presence here.

But that goal has been delayed in part because of sectarian tensions which flared after the Samarra shrine bombing.

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Associated Press writers Bushra Juhi and Sinan Salaheddin in Baghdad contributed to this report.