A motorcycle bomb in southern Afghanistan killed four civilians and injured eight, a government official said Wednesday. The bomb exploded in a crowded area in Spin Boldak district of Kandahar province on Wednesday morning, Parwiz Najib, a senior official in the provincial governor's office said. "A woman and a child were among the four killed in the explosion," he was quoted as saying by DPA. Najib said that seven others and a border policeman were also injured in the explosion.