In this photo provided by the Iranian Students' News Agency, Revolutionary Guard members carry a wounded comrade after a shooting during a parade in Ahvaz, Iran, on September 22.
The official IRNA news agency said a woman and a child were among the wounded. Ahvaz is in the centre of Khuzestan province, where there have been sporadic protests by the Arab minority in predominantly Shi'ite Iran. "There are several killed and injured", a correspondent told state television, which later reported that 20 people were wounded.
Photos shared by a state news agency show a man in military fatigues with blood running down his back being helped towards a auto by a group of men.
No group immediately claimed responsibility for the assault in Ahvaz, which saw gunfire spray into a crowd of marching Guardsmen, bystanders and government officials watching from a nearby riser.
The semi-official Fars news agency, which is close to the Revolutionary Guard, said two gunmen on a motorcycle wearing khaki uniforms carried out the attack.
Top Iranian diplomat Mohammad Javad Zarif vowed to respond "swiftly and decisively" after gunmen opened fire in Ahvaz on Saturday leading to multiple casualties.
He added that the gunmen were "terrorists recruited, trained, armed and paid by a foreign regime". According to the semiofficial ISNA news agency, nine of those killed were members of the military.
The report Saturday described the assailants as "Takifiri gunmen", a term previously used to describe ISIS.
It has been reported that two of the assailents have been killed and two others arrested, Mehr reported.
ISNA said an unnamed spokesman for the Revolutionary Guards blamed Arab nationalists backed by Saudi Arabia for the attack.
Iran was holding a number of parades in cities including the capital Tehran and the port of Bandar Abbas on the Gulf to mark the start of the country's 1980-88 war with Iraq.