Sky News:- At least 29 people have died and 53 more are injured after gunmen opened fire on a military parade in Iran, according to state media.
A child and a woman are among the injured following the attack in Ahvaz, the Islamic Republic News Agency (IRNA) reported.
The agency claims “four or five terrorists were gunned down by the police”.
The attack began half an hour after the parade began at 8.30am local time (6am in the UK).
Foreign minister Mohammed Javad Zarif has blamed the attack on “regional terror sponsors” and their “US masters”.
“Iran will respond swiftly and decisively in defence of Iranian lives,” he wrote on Twitter.
Both Islamic State and an Iranian ethnic Arab opposition movement called the Ahvaz National Resistance have claimed responsibility for the attack, but neither has provided evidence.
Earlier on, state TV report said the assailants were “Takfiri gunmen,” a term sometimes used to describe Islamic State.
“Shooting began by several gunmen from behind the stand during the parade. There are several killed and injured,” a correspondent told state television.
The shooting lasted for about 10 minutes.
Dramatic footage in a video being shared on social media shows the crowd dropping to the floor as the rattle of gunfire is heard in the background.
Those in military uniform and civilians, including small children, can also be seen crouched over while running for safety in the clip.
A second video capturing the aftermath of the attack shows a chaotic scene of people fleeing and paramedics trying to help the injured.
Photos shared by a state news agency show a man in military fatigues with blood running down his back being helped towards a car by a group of men.
A picture of a bloodied backpack was also shared.
The parade in the southwestern city was being held to mark the anniversary of the start of the eight-year war with Saddam Hussein’s Iraq in 1980.
Britain’s ambassador to Iran Rob Macaire said: “A shocking terrorist attack. Wherever it happens terrorism must be condemned. All our condolences to the families of the victims.”
IS attacked Iran’s parliament and the shrine of Ayatollah Ruhollah Khomeini in Tehran on 7 June 2017. At least 18 people were killed and more than 50 wounded in the attack.
The assault shocked Tehran, which largely has avoided militant attacks in the decades after the the 1979 Islamic Revolution, which saw Khomeini topple the Western-backed shah to become Iran’s first supreme leader until his death in 1989.