US and Iraqi forces raided the Shi'ite neighborhood of Sadr City on Sunday, bombing four houses and wounding six civilians, Iraqi police said. The operation began early in the morning, when US forces backed by Iraqi troops began searching houses in the area, known as a hotbed of Shi'ite insurgent groups. Aircraft flew over the neighborhood during the raid and carried out airstrikes on four houses, reducing one to a pile of bricks and rubble, police and witnesses said. The occupants of the destroyed house had apparently fled before the raid. Several cars were also charred and badly damaged. US military spokesmen had no immediate comment.