Yousuf Ahmadi told the agency: "We carried out the bombing. It was a car bomb that was exploded by one of our mujahid [fighters] using a remote-controlled device."
Andiwal said there was no "military presence" in the area at the time of the blast.
"All the casualties are civilians," he said.
A police officer was killed earlier on Wednesday in a roadside bombing in Helmand.
A US-led invasion of Afghanistan forced the Taliban government from power. Thousands of people have died amid the fighting against the Kabul government and Afghan security forces.