At least 22 people died Wednesday in a fresh bout of violence in Iraq, including eight people in a US strike on Baghdad's Shiite enclave of Sadr City, while the police found rockets in a big weapons cache in the south, according to dpa. At least eight people were killed and 13 injured Wednesday when US aircraft bombed positions of the Mahdi Army militia in Sadr City in eastern Baghdad, according to witnesses. Fresh clashes between the Shiite Mahdi Army and US forces broke out Tuesday evening, the witnesses said. Iraqi special forces backed by US troops conducted operations in the area "to reduce special groups' criminal activity," the US military said in a statement Wednesday. Special groups is the term the military used to describe Iranian- backed Shiite militiamen. Seven suspected militiamen were arrested during the operation on Tuesday. The military said its aircraft destroyed gunmen's positions in Sadr City Tuesday but could not ascertain whether people were killed or injured in the strike. In south-east Baghdad, police killed eight gunmen during a raid in Amin district, General Qasim Atta, the spokesman for the Baghdad operations, told the Voices of Iraq (VOI) news agency. A policeman was killed and 10 others injured in the operation. Explosive were detonated and guns found. The general did not reveal the identity of the slain gunmen. In the northern sity of Mosul, four Iraqi army soldiers were killed in clashes with insurgents, a security source said. "An army patrol was engaged in clashes with a terrorist group Wednesday in a Mosul district, about 400 kilometres north of Baghdad, which left four patrol members dead," the source added. Mosul has recently seen a surge in violence, which is mostly blamed on Sunni insurgents regrouping in northern Iraqi provinces after they were driven out of Baghdad and surrounding areas. In the western Anbar province, a US soldier was killed Tuesday while on patrol, the US military said. The killing brings the death toll among US soldiers since the 2003 Iraq war to 4,073. Police discovered a big weapon cache on a farm north of Karbala, 110 kilometres south of Baghdad, VOI quoted the city police chief, General Raid Shakir, as saying. The cache, which was buried about five metres underground, contained 25 SBG-9 rockets, 25 rocket launch pads and other weapons.