An explosion apparently targeting US troops struck a local council building Tuesday in Baghdad's Shi'ite Sadr City district, killing at least six Iraqi civilians, police and witnesses said. The US military confirmed a blast near the district advisory council building in Sadr City but did not immediately release more details pending reports from the scene. Ten civilians were wounded in the blast, which occurred shortly after 9 a.m. near the deputy council chief's office as Americans approached, police officials said, speaking on condition of anonymity because they weren't authorized to release the information. Witnesses said US troops had cordoned off the area. The explosion came a day after a gunman opened fire on US soldiers attending a municipal council meeting southeast of Baghdad, killing two of them and wounding four other Americans.