Two soldiers from the U.S.-led coalition were killed in southern Afghanistan when their patrol vehicle struck a roadside bomb, the coalition said Sunday. The soldiers had been conducting a security patrol together with Afghan troops on Saturday in Kandahar province when the incident occurred. A coalition statement did not release the nationalities of the two soldiers. Separately, in neighboring Zabul province, Afghan and coalition forces launched an operation targeting Taliban insurgents Saturday. The ensuing one-hour gun battle in Shahjoy district left four insurgents dead and three wounded, said Zabul deputy provincial police chief Faridullah Khan. Three insurgents were arrested, Khan said, adding that there were no casualties among Afghan or coalition forces. Last year was the most violent in Afghanistan since the 2001 U.S.-led invasion. The U.N. says more than 8,000 people died in insurgency related violence, according to a report of the Associated Press.