Five Iraqi civilians, including two children, were killed and 17 were wounded early Monday after militiamen attacked a U.S.-run military base south of Baghdad, according to police. The clashes in Diwaniyah, a city 130 kilometers (80 miles) south of Baghdad, began when fighters from the Mahdi Army militia, which is loyal to cleric Muqtada al-Sadr, fired at least a dozen mortar rounds at the base, according to a police officer. Eight of the mortar rounds landed on the base, but there was no immediate word on casualties or damage. A message left for the U.S. military asking for comment wasn't immediately returned, The Associated Press reported. The four other mortar rounds hit the city's nearby joint security center, which is run by Iraqi, U.S. and Polish forces. Mahdi Army fighters emerged from alleys and swarmed the building, the police officer said, adding the clashes lasted about 30 minutes.