A barrage of mortar rounds fell on and around a power station in the southern Iraqi city of Basra late on Friday (November 3), wounding four Russian engineers, director of the plant said. He said that several mortar shells fell on the building of al-Najibiya power plant and an adjacent building, which is used as a resident place of the Russian engineers, wounding four, one of them seriously. Iraq's second largest city of Basra, 550 Km south of Baghdad, has been relatively calm over the past year and a half, although there are occasional outbreaks of violence. British forces are responsible for security in the city and other towns in southern Iraq. Meanwhile, a roadside bomb exploded near a passing U.S. convoy in central Baghdad on Saturday (November 4), but there were no reports on casualties, police said. The blast took place in al-Nidhal street and U.S. forces immediately sealed off the site. Television footage showed a civilian car on fire and black smoke billowing from it as a U.S. Stryker could be seen driving past. The U.S. military could not be reached for comment. Bombs assembled in makeshift factories, then planted discreetly along roadways and detonated by remote control have become Sunni Arab insurgents' weapon of choice in their three-year guerrilla war against U.S. forces and the Iraqi government. Two civilians were killed and five people were wounded, including four policemen when a car bomb exploded in eastern Baghdad on Saturday (November 4), police said. They said that the car was parked in Baghdad's eastern district of Talbiya. Meanwhile, a woman was killed and three people were wounded in a car bomb blast in a town south of Baghdad on, police said. They said that the car was parked near the post office of Mahmoudiya town, about 30 km (20 miles) south of Baghdad. The town, which has a mixed Shi'ite and Sunni population, has been the scene of frequent bombings and shootings recently. On Friday (November 3), four civilians were wounded when a mortar round landed at houses in Abu Dsheer residential area, in the outskirts of Baghdad's dangerous district of Dora. "We were sitting outside the house when we heard the sound of the firing of a mortar and we said it would fall on us and it did," said Rageb Abdul Haq, who was wounded in the back of his head.