Baghdad, Iraq ? Iraqi troops backed by U.S. jets raided a Shiite stronghold Friday in the capital, killing and wounding dozens of people in a crackdown on militias blamed for much of Iraq’s worsening sectarian violence.

At least 17 others died in a wave of bombings and mortar attacks against mostly Sunni mosques in the Baghdad area and northern Iraq. A Sunni cleric also was kidnapped in the capital, a Sunni official said.

The raid began before dawn in Sadr City, a Shiite district of east Baghdad, as Iraqi troops backed by the Americans swooped down on a building where an undisclosed “insurgent leader” was holed up, a U.S. statement said.

Gunmen opened fire from the roof with automatic weapons and rocket-propelled grenades, triggering a firefight in which an estimated 30 to 40 “enemy fighters” were killed, the U.S. said. There were no American or Iraqi government casualties, the statement added.

The insurgent leader was captured, U.S. spokesman Maj. Gen. William Caldwell said. He would not identify him but said he and his followers had kidnapped, tortured and murdered Iraqi citizens and tried to smuggle weapons from Syria.

Iraqi mothers stand with their children next to a spray of bullet holes from a late night firefight between insurgents and Iraqi and coalition soldiers following a raid in the Sadr City area of Baghdad, Iraq. Iraqi soldiers clashed with gunmen Friday in the Shiite district of Baghdad and officials said as many as nine people were killed and 34 wounded.

Residents of Sadr City said they thought the raid targeted Abu Diraa, a commander of a breakaway faction of the Mahdi militia, led by radical cleric Muqtada al-Sadr. Several residents insisted Abu Diraa had escaped but offered no proof.

Prime Minister Nouri al-Maliki, a Shiite, has promised to disband sectarian militias, blamed for the tit-for-tat killings that have heightened tensions between Shiites and Sunnis and raised fears of civil war.

But the raid enraged many of the 2.5 million Shiites in Sadr City as rumors spread through the crowded slum district that most of the dead were civilians killed as they slept on their rooftops. Many Iraqis sleep on roofs during the sweltering summer months because the electricity crisis means they don’t have fans and air conditioning.

An al-Sadr aide, Sheik Abdul-Hadi al-Darraji, said 11 civilians were killed and dozens wounded.

“This is a big escalation from the American side,” he said. “I condemn all the silence toward such violations and I call for the withdrawal of the American forces.”

Lt. Kadim Abbas Hamza of the Sadr City police said nine people, including a woman, were killed and 14 were wounded. He also said eight people were arrested. A hospital official said seven people were killed and 34 wounded.

Caldwell said the operation was planned and directed by Iraqis with U.S. troops in a supporting role. However, an Iraqi army officer said the Americans gave them a list of people to be arrested in advance of the raid.

Caldwell said U.S. jets fired three precision weapons during the 45-minute battle and U.S. troops manning a security cordon took fire from “multiple positions.”

The raid occurred a day after U.S. and Iraqi troops arrested a top regional commander of the Mahdi militia near the southern city of Hillah, a U.S. statement said. Adnan al-Unaybi was commander of Mahdi militiamen in the Euphrates valley south of the capital, the statement said.

Both moves appeared to signal a crackdown on Shiite militiamen. Shiite gunmen are believed to be holding Sunni parliament member Tayseer al-Mashhadani, who was seized in a Shiite neighborhood nearly a week ago.

In another sign of sectarian tensions, a series of bombs and a mortar blast struck four Sunni mosques in the Baghdad area and a Shiite mosque in the northern city of Sinjar, killing a total of 17 people and wounding more than 50, police said.