Atta Jan, head of the Zabul provincial council, said Monday that two children and a woman were among those killed in the explosion the night before in the Shinkay district.
In the northern Kunduz province, meanwhile, the Taliban battled police three days after declaring the start of their annual springtime offensive.
Provincial Gov Omer Safi says reinforcements have been sent in. He says there have been casualties on both sides, but was unable to provide precise figures.