The incident happened at about 9:58 a.m. local time (0458 GMT) in Wana district of the province, where an improvised explosive device went off near the vehicle, the sources from the district's police told Xinhua.
The injured, including police personnel and passersby, were shifted to a nearby hospital for medical treatment, the sources added.
No group has claimed responsibility for the attack yet.
The area has been cordoned off for investigations.