A car packed with explosives rammed an army vehicle in troubled southern Afghanistan Saturday, killing three soldiers, the latest attack in a surge of violence ahead of the nation's presidential polls. Three other troopers were wounded in the suicide attack in Shahjoy, an insurgency-wracked district in the province of Zabul, the defence ministry said in a statement. "Today... an explosive-laden Surf (vehicle) targeted a National Army Ranger (car), as a result of which three soldiers were killed and three others were wounded," the statement said.