Gunmen kill 24 Revolutionary Guards in attack on Iran military parade

State television said the assault, which wounded more than 60 people, targeted a stand where Iranian officials had gathered to watch an annual event marking the start of the Islamic Republic's 1980-88 war with Iraq.

The Islamic Revolutionary Guards Corp (IRGC) have been the sword and shield of Shi'ite clerical rule since Iran's 1979 Islamic Revolution. The Guards also play a major role in Iran's regional interests in countries such as Iraq, Syria and Yemen.

A video distributed to Iranian media showed soldiers crawling on the ground as gunfire blazed in their direction. One soldier picked up a gun and got to his feet as women and children fled for their lives.

Ali Hosein Hoseinzadeh, deputy governor in Khuzestan province, was quoted as saying the death toll was expected to rise. One of those killed was a journalist.

The bloodshed struck a blow to security in OPEC oil producer Iran, which has been relatively stable compared with neighbouring Arab countries that have grappled with upheaval since the 2011 uprisings across the Middle East.

There was no immediate claim of responsibility for the attack in the city of Ahvaz.

State television blamed "takfiri elements", a reference to Sunni Muslim militants, for the attack. Ahvaz is in the centre of Khuzestan province, where there have been sporadic protests by the Arab minority in predominantly Shi'ite Iran.

Foreign Minister Mohammed Javad Zarif said the assault was the handiwork of "regional terror sponsors", language that usually refers to Iran's enemies Saudi Arabia and Israel, and "their U.S. masters". He vowed Tehran would respond decisively.

ISNA said an unnamed spokesman for the Revolutionary Guards blamed Arab nationalists backed by Saudi Arabia for the attack.

The Revolutionary Guards are the most powerful and heavily armed military force in the Islamic Republic and also have a vast stake worth billions of dollars in the economy.

Kurdish militants killed 10 Revolutionary Guards in an attack on an IRGC post on the Iraqi border in July, Iran's semi-official Tasnim news agency reported, the latest bloodshed in an area where armed Kurdish opposition groups are active.

Iran will be scrambling to determine the motives for the Saturday's high-profile attack as it faces growing U.S. pressure.

President Donald Trump decided in May to pull the United States out of the 2015 international nuclear deal with Tehran and reimpose sanctions in a bid to isolate the Islamic Republic.

A video on state television's website showed confused soldiers at the scene of the attack. Standing in front of the stand, one asked: "Where did they come from?" Another responded: "From behind us."

Four militants carried out the attack and two of them were killed, according to ISNA. There has been no claim of responsibility for the attack in the city of Ahvaz.

Iran was holding similar parades in several cities including the capital Tehran and the port of Bandar Abbas on the Gulf.

"Shooting began by several gunmen from behind the stand during the parade. There are several killed and injured," a correspondent told state television.

Tensions between mainly Shi'ite Iran and mostly Sunni Saudi Arabia have surged in recent years, with the two countries supporting opposite sides in wars in Syria and Yemen and rival political parties in Iraq and Lebanon.

Attacks on the military are rare in Iran.

Last year, in the first deadly assault claimed by Islamic State in Tehran, 18 people were killed at the parliament and mausoleum of Ayatollah Ruhollah Khomeini, the founder and first supreme leader of the Islamic Republic.