KABUL (AFP) - An old mortar shell exploded as a group of children played with it in Afghanistan, killing three of them and wounding another three, the interior ministry said Thursday. The shell, apparently left over from Afghanistans decades of war, exploded on Wednesday in the province of Kapisa north of the capital Kabul, it said in a statement. The mortar shell explosion killed three children and wounded three other children, it said. There are regular blasts involving ordnance left over from Afghanistans decades of war, despite efforts of mine clearing teams who have been operating here for years.