HERAT, Afghanistan: At least 11 civilians including four women and three children were killed when a roadside bomb struck a bus in Afghanistan, officials said Sunday.

The attack occurred on Saturday evening in the western province of Badghis.

No group has claimed responsibility for the blast.

An official from the province, Khodadad Tayeb, confirmed the toll and said that the bus fell into a valley after it was hit by the bomb.

Saturday's attack came after a series of blasts targeted passenger buses in Kabul this week.

The surge in violence across Afghanistan comes as the US military continues to withdraw its remaining 2,500 troops from Afghanistan.

President Joe Biden has ordered the military to complete the pullout by the 20th anniversary of the September 11 attacks.