A roadside bomb on Wednesday morning hit a passenger bus in Nimruz province in southwest Afghanistan, killing 20 people and wounding 25 others, local official said.

The incident happened at around 07:00 a.m. local time between Dilaram district of the province and Bagwa district of the neighboring Farah province, Ghulam Dastgir Azad, governor of Nimruz province, told Xinhua, adding that the dead and wounded include many women and children.

"Many of the wounded are in critical conditions," said Azad, adding "casualties could further rise."

He said the some of the wounded have been rushed to a NATO hospital for treatment.