BAGHDAD, Iraq — American and Iraqi troops swept the oil-rich region of Kirkuk for suspected insurgents and captured dozens, while drive-by shootings, roadside bombings and sectarian violence killed at least 29 people in Iraq today.

A bombing outside a Sunni Muslim mosque after prayers this morning killed five worshippers and wounded 15 people in the city of Khalis, northeast of Baghdad, the army said.

Gunmen in vehicles killed three policemen in west Baghdad and three power station workers headed to their jobs in Taji, just north of the capital, police said.

In southern Baghdad's Saydiyah district, gunmen killed four pastry shop employees, police said. Nearby, a roadside bomb killed a policeman.

Retaliatory killings between Shiite and Sunni Muslims have become increasingly common in the capital since the Feb. 22 bombing of an important Shiite shrine that unleashed the continuing rash of sectarian murders. Police said they found 13 bodies, blindfolded and shot, today in the Binok, Kazimiyah and Sadr City neighborhoods.

Mortar rounds fell on homes in south Baghdad and the northern city of Tal Afar, wounding about 10 people, mainly children.

Meanwhile, soldiers of the 1st Brigade Combat Team, 101st Airborne Division joined Iraqi troops in a sweep of five villages outside the city of Kirkuk, 180 miles north of Baghdad. Forty suspected insurgents were picked up in Hawija, police said.

A day earlier, a U.S. military spokesman asserted that major violence is largely confined to just three of Iraq's 18 provinces, where fighting raged on Thursday with at least 58 people killed in execution-style slayings, bombings and gunbattles.

As insurgent forces raised the stakes with the attacks, the U.S. military said late Thursday it was in the second day of an operation with Iraqi soldiers "to disrupt anti-Iraqi forces and to find and destroy terrorist caches in the Abu Ghraib area west of Baghdad."

The military statement said 1,400 personnel were involved in the operation — termed Northern Lights — and had captured "two persons of high-value interest and 16 suspected terrorists." Two large weapons caches also were discovered, the military said.

As Iraqi soldiers and police have begun patrolling more territory, U.S. forces have become less visible in many areas and less easy to target. Also, the nature of the violence has shifted from assaults on American troops to battles rooted in sectarian conflict between Sunni and Shiite Muslims.

More than 1,000 people have died violently in Iraq, mainly in and around Baghdad, since the shrine bombing in Samarra, a city north of Baghdad in Salaheddin province.