The incident took place around 10.00 am (local time) in Sancharak district after the suicide bomber targeted Rahim Ayoubi, a former Jihadi leader, Khaama Press reported.
Ayoubi survived the attack unhurt but four members of his family were killed, the official said.
The victims were two sons and two nephews of Ayoubi. Another member of his family was also wounded.
Ayoubi had left his family members inside his vehicle as he was visiting a cemetery when the suicide bomber targeted the vehicle, the official added.