Police say a roadside blast in southern Afghanistan has killed four policemen. Khan Mohammad, a police official in Kandahar province, says the blast struck a patrol in Maywand district on Saturday. Mohammad says four policemen were killed and another was wounded. Separately, Mohammad Nabi Khan, another police official, says a suicide bomber attacked a police checkpoint near the main NATO base just outside Kandahar city. Khan says a child and a policeman were wounded in the explosion Saturday.