KABUL, Afghanistan (AP) — An Afghan official says a roadside bomb explosion hit a passenger bus in western Farha province, killing at least 18 people including women and children.

Mohibullah Mohib, spokesman for the provincial police chief in Farah, says six people were wounded in the bombing Wednesday morning in Bala Buluk district.

Mohib insisted the casualty numbers in the initial report could rise. He added ambulances have taken victims to hospitals in both Herat and Farah provinces.

No one immediately claimed responsibility for the attack. Taliban insurgents are active in the region and use roadside bombs to target government officials as well as Afghan security forces, though civilians become victims of the planted bombs.