A roadside bomb ripped through a minibus in troubled southern Afghanistan on Tuesday, killing four civilians and wounding six other people, officials said. The incident took place in the Nad Ali district of Helmand province, Daud Ahmadi, spokesman for the provincial governor, told media. "The blast killed four civilians and wounded six others," he said. NATO's International Security Assistance Force (ISAF) scrambled to the scene and ferried four of the wounded to one of its military hospitals and the other two to a provincial hospital, Ahmadi said. Elsewhere in the south, Afghan police defused Tuesday three bombs planted along the Kandahar-Helmand highway, the interior ministry said. Estonian Foreign Minister Urmas Paet was in Helmand on Tuesday to meet the more than 100 Baltic soldiers stationed in the province, Ahmadi said. The spokesman had said earlier that the visiting official was Estonian Defence Minister Jaak Aaviksoo. He later telephoned to correct his mistake.