BAGHDAD, (Reuters) – U.S. airstrikes on a Shi’ite neighbourhood in Baghdad overnight killed at least 14 people including one woman and destroyed 11 houses, Iraqi police and residents said on Thursday.

The U.S. military said U.S. special forces called in the strikes after coming under fire from gunmen on rooftops during an operation against Shi’ite militants suspected of killing local police and Sunni Arabs.

It said the soldiers, accompanied by Iraqi special forces, directed aircraft to fire on two buildings where gunmen were holed up. Two other buildings sustained minor damage. “The targeted Shi’ite extremists are part of a terrorist cell … responsible for attacking local police and conducting illegal checkpoints to intimidate, extort and murder local citizens. The teams also conducts extra-judicial killings of Sunnis,” the military said in a statement. The statement did not say if any militants or civilians were killed in the air strikes.

U.S. and Iraqi forces have stepped up raids against Shi’ite militant cells in Baghdad as part of a wider crackdown on sectarian violence that has killed tens of thousands of Iraqis.

U.S. commanders and President George W. Bush said this week that the seven-month offensive had improved security in Iraq. The top U.S. military commander in Iraq, General David Petraeus, suggested in an interview with ABC News on Tuesday he would recommend a cut in U.S. troop numbers around March when he testifies before the Democrat-controlled Congress next week.

Petraeus and Ambassador Ryan Crocker will deliver their long-awaited assessment on Bush’s decision to send 30,000 additional soldiers to Iraq, raising force levels to 160,000. Democrats and some top Republicans, angered at the failure of Iraq’s leaders to pass laws aimed at fostering reconciliation between majority Shi’ites and Sunni Arabs, want U.S. forces to start leaving Iraq.

Two police sources said 14 people were killed and nine wounded in the air attack on Washash, a poor Shi’ite neighbourhood in western Baghdad’s Mansour district. They said the operation took place in the early hours.

Reuters television footage showed at least 11 buildings caved in or levelled in three adjoining streets in the densely packed neighbourhood, where fighters loyal to anti-American Shi’ite cleric Moqtada al-Sadr are known to operate.

A Reuters cameraman saw residents pulling the body of a woman from the rubble of one house, while one man picked up flesh from the street and placed it into a plastic bag. “This is a catastrophe. We have pulled 24 bodies from the rubble,” said an official at Sadr’s office in Washash who declined to be named.

Residents said the aerial bombing was preceded by clashes between U.S. soldiers and gunmen. One man said soldiers had raided his home in search of a suspect and had confiscated mobile phones and separated the men from the women. Many residents were sleeping on the roofs of their houses at the time, trying to keep cool in the oppressive summer heat. “We are a peaceful neighbourhood. Why is this happening to us?” said Abu Talib, an elderly man with a white beard.

Wamidh Abdul Jabbar, a doctor, was sleeping with her children on the roof of her home when she heard machinegun fire. “Then we heard the planes bombarding and the sound of buildings crashing. I took my children and we hid under the stairs,” she said.

The U.S. military’s use of attack helicopters and warplanes in Baghdad has angered the government in the past.