Police officials say today's attack happened in the town of Taji, 20 kilometres north of the Iraqi capital where the bomber detonated his explosives as the pilgrims were getting off the bus at a gas station.
Hospital officials said an Iranian woman and the Iraqi bus driver were among the dead. Also, at least 11 Iranian pilgrims were wounded in the attack. The pilgrims were returning from the holy Shiite city of Samarra.
All officials spoke on condition of anonymity because they are not authorized to talk to the media.