Afghan and Pakistani border guards exchanged fire in a row over a child caught smuggling flour, leaving an Afghan guard and a civilian wounded, officials said Sunday. Saturday's gunfight forced the closure of the Torkham border, the busiest between the neighbours, for about 90 minutes, a Pakistani official said. The commander of the Afghan border police said the dispute erupted after Pakistan's guards assaulted a young boy among several who smuggle sacks of flour across the border every day. One of his men confronted the Pakistanis and they started physically fighting, said the commander named only Shamamud. Guards exchanged fire and an Afghan was wounded, he said. In Pakistan, an official said the Pakistani guards had tried to stop the boy smuggler and were opposed by the Afghans. The two sides opened fire and an Afghan soldier was wounded, along with a civilian, he said on condition of anonymity. Afghanistan depends on its neighbours for flour, a staple, but Pakistan recently halted exports amid its own shortfalls. Prices have doubled in parts of Afghanistan in recent months. Pakistan has blamed its shortages on smuggling, with boys aged around 10-12 employed to carry it over the border into Afghanistan. There was a similar gunfight at the same border crossing on April 14 but there were no casualties.