A NATO patrol shot and killed a policeman Tuesday as troops left their base in an insurgency-wracked district in southern Afghanistan, NATO said. The policeman, armed and wearing civilian clothes, turned toward the patrol and was gunned down, mistaken for an insurgent, NATO said in a statement. The troops gave him first aid and took him to the closest medical facility, where he died of his wounds, the statement said, adding that no further details would be released until an investigation has been completed. Full Story