AHVAZ, Iran - In one of the deadliest attacks in the country in years, Iran suffered a bloody assault on Saturday, after a group of gunmen opened fire on a military parade in Ahvaz city. 

The attack left 24 people dead, including 12 civilians and 12 members of Iran's powerful security establishment - the Islamic Revolutionary Guards Corp.

According to Iran's state-run IRNA news agency, gunmen attacked the annual military parade that was being held in Ahvaz city, in the country's oil-rich southwest region. 

Iran's State television said that gunmen targeted a stand where Iranian officials had gathered to watch the annual event, which marks the start of the Islamic Republic's 1980-88 war with Iraq.

Apart from the 24 people killed, state media confirmed that over 60 others were injured in the attack. 

In a statement issued on state television, Brigadier General Abolfazl Shekarchi, a senior spokesman for Iran's armed forces said, "Three of the terrorists were killed on the spot and a fourth one who was injured died in hospital."

Further, the report in IRNA quoted another senior official as pointing out, "There are a number of non-military victims, including women and children who had come to watch the parade."

The Iranian media broadcast a video that had been distributed by officials, which showed soldiers ducking and crawling on the ground as the gunmen opened fire.

In a report, state television also claimed that Sunni “takfiri terrorists” had carried out the assault.

Further, a spokesman for Iran’s Revolutionary Guard Corps initially blamed minority Arab separatists for the bloodshed.

In a statement, the spokesman for the elite forces, Ramezan Sharif accused Iran's regional rival - Saudi Arabia, of funding the militant group that was being blamed for the attack. 

Meanwhile, in a statement on Twitter, Iranian Foreign Minister Mohammad Javad Zarif vowed to “respond swiftly and decisively in defense of Iranian lives.”

Zarif wrote, "Terrorists recruited, trained, armed & paid by a foreign regime have attacked Ahvaz. Children and journos among casualties. Iran holds regional terror sponsors and their US masters accountable for such attacks.”

Subsequently, the Ahwaz-based separatist group called the Patriotic Arab Democratic Movement claimed responsibility for the attack.

According to IRNA, the group is supported by "foreign antagonists," including Saudi Arabia.

The report quoted Gholam-Reza Shariati, the Governor of Khuzestan as saying, "The terrorists disguised as Islamic Revolution Guards Corps (IRGC) and Basiji (volunteer) forces opened fire to the authority and people from behind the stand during the parade."

Further, Deputy Governor of Khuzestan province, Ali Hosein Hoseinzadeh was quoted as saying that the death toll was expected to rise.

Ahvaz, which is right at the centre of the Khuzestan province, has witnessed sporadic protests by the Arab minority in recent months.

However, Saturday's attack were said to be the most high-profile attack in years and a rare one that targetted the powerful Islamic Revolutionary Guards Corp that have been the sword and shield of Shi'ite clerical rule since Iran's 1979 Islamic Revolution.