Continuing violence in the oil-rich Shi'ite heartland on Saturday (October 21) was testing the ability of Iraq's Shi'ite-led government to rein in militias and other armed groups accused of fomenting violence that has pushed Iraq close to civil war. National Security Minister Shirwan al-Waeli, was sent to the southern city of Amara on Friday (October 20), after clashes between tribal divisions left at least 25 dead in two days. "The problem is not that big yet. We do not have a full scale attack or infiltration at the moment. There have been clashes between gunmen and police," he said. One civilian was killed and three others wounded in a car bomb blast targeting a passing patrol of Iraqi police on Saturday (October 21) , police said. The blast took place in the Bab al-Muadham district of central Baghdad. The blast was the fourth major bomb attack of the day. Earlier a suicide bomber blew himself up inside a commuter bus, killing four civilians and wounded 15 others. The surge of violence came one day after the signing of a declaration by Iraqi Sunni and Shi'ite clerics in the city of Mecca, prohibiting infighting between Muslims. To the north of the capital, the morgue of a hospital in Tikrit received on Saturday the corpses of 10 men, riddled with bullets in various parts of their bodies. The bodies were found in an area near, 80 km (50 miles) north of Baghdad, a hospital source said. The dumping of bodies bearing signs of torture and killed execution-style has become a feature of a sectarian "dirty war" being waged among Iraqi armed factions. Official figures and anecdotal evidence suggests an increase in such killings since the destruction of a major Shi'ite shrine in Samarra on February 22 sparked reprisal attacks.