KABUL, Afghanistan — A woman and two children were accidentally killed in fighting in western Afghanistan that erupted as Afghan and international forces pursued a Taliban militant known to smuggle foreign fighters and weapons from Iran, NATO said Saturday.Separately, one US service member died Saturday and another was killed Friday following insurgent attacks in southern Afghanistan. NATO did not disclose details about their deaths. Twenty US service personnel have been killed so far this month in the war.In the west, six insurgents were killed as they got out of a vehicle and several other suspected militants were detained during the operation in the Pusht Rod district of Farah province, the coalition said. An air weapons team then fired on the vehicle, which subsequently exploded. The joint force, which later found the three civilians dead at the scene, believed the vehicle might have been loaded with homemade explosives."We deeply regret what occurred on yesterday's operation," US Army Col. Rafael Torres, a spokesman for NATO, said in expressing condolences to relatives. "We are taking a step-by-step approach in investigating what went wrong."