Zabul's governor, Mohammad Ashraf Nasiri, says the crash, which took place this morning near the provincial capital of Qalat was a traffic accident, most likely due to human error.
The bus was en route to Kandahar province. The collision ignited a fire that burned half the bus and caused most of the fatalities. Nasiri says four children and five women were among those killed.
He says bad roads and reckless driving have caused scores of such accidents in the country's south.