Gunmen have attacked a military parade in the south-west Iranian city of Ahvaz, killing at least eight members of the Revolutionary Guard and wounding 20 people, state media said.
The state-run IRNA news agency reported that the wounded included a woman and a child but did not elaborate.
Earlier reports on Saturday described the assailants as Takfiri, a term previously used to describe Islamic State.
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.
State television showed images of the immediate aftermath, with paramedics seen helping someone in military fatigues lying on the ground. Other armed security personnel shouted at each other in front of what appeared to be a viewing stand for the parade.
The semi-official ISNA news agency published photographs of the aftermath, with bloodied troops in dress uniforms helping each other away from the scene on Ahvaz’s Quds, or Jerusalem Boulevard.
There was no immediate claim of responsibility.
Islamic State carried out a deadly assault on parliament and the shrine of Ayatollah Ruhollah Khomeini in Tehran in June last year. At that point, that had been the only attack by the Sunni extremists inside Shia Iran, which has been deeply involved in the wars in Iraq and Syria where Isis once held vast territory.
Ahvaz is the capital of Iran’s oil-rich Khuzestan province, where Arab separatists have attacked oil pipelines in the past.