KABUL — Afghan officials say a roadside bomb has hit a public bus in a restive province bordering Kabul, killing at least nine civilians and wounding 22.

Deputy Wardak provincial chief police Gen. Abdul Razaq Quraishi said Monday's explosion took place in the Sayed Abad district.

Wardak is located next to Kabul and is considered a gateway and staging area for militant attacks on the capital.

A spokesman for the governor said the bus was traveling from eastern Ghazni province to the capital.

The deadly attack capped a week of violence around Afghanistan that has seen about 80 people killed, including six Americans and numerous insurgents.

The violence comes as Afghanistan's spring fighting season gets fully underway. Fighting usually abates during the country's harsh winter season.