KABUL - A roadside bomb tore through a bus in western Afghanistan on Wednesday, killing at least 32 people, including children, a provincial official said.

Mohibullah Mohib, spokesman for the police chief in Farah province, said the explosion also wounded 15 people. Most of the wounded were said to be in critical condition, indicating the death toll could rise. The bus was travelling on a main highway between the western city of Herat and the southern city of Kandahar. No one immediately claimed responsibility, but the Taliban operate in the region and frequently use roadside bombs to target government officials and security forces.

The Islamic State group’s affiliate in Afghanistan is also known to have been behind attacks in the area.

The Taliban have kept up a steady tempo of attacks even as they have held several rounds of peace talks with the United States aimed at ending the 18-year war.