"Some 22 people involved in the attack in Ahvaz have been identified and arrested… weapons, exclusive material and communication equipment were seized in the house that belonged to the five-member terrorist group that carried out the attack," a statement from the intelligence agency said, according to Tasnim News Agency.
The military reportedly vowed a "deadly and unforgettable" response to the terrorist attack which was conducted in the southern city of Ahvaz during an annual military parade.
— Javad Zarif (@JZarif) September 22, 2018
Twelve members of the Islamic Revolutionary Guard Corp (IRGC) were reportedly killed after the terrorists opened fire. Children and journalists were also among the casualties, according to Iranian Foreign Minister Javad Zarif. "Terrorists recruited, trained, armed & paid by a foreign regime have attacked Ahvaz," he wrote. "Iran holds regional terror sponsors and their US masters accountable for such attacks. Iran will respond swiftly and decisively in defense of Iranian lives."
IRGC Lieutenant Commander Brigadier General Hossein Salami blamed Israel, the United States and Saudi Arabia for the attack in a speech aired Monday for the victims's funerals. He promised that Iran would have a "devastating" response to the attackers and their sponsors.
Later Monday, US Defense Secretary James "Mad Dog" Mattis said he was not concerned with Iran's threat of revenge, adding that the suggestion the US had anything to do with the attack "ludicrous."
Israel and Saudi Arabia, for their parts, do not seem to have commented yet on the allegation.
The Islamic State group [Daesh] and a terrorist group local to the Iranian region where the attack was conducted called Al-Ahvaziya have both claimed responsibility for the attack. The former leader of the little-known terror group, Ahmad Mola Nissi, was gunned down in front of his home in The Hague, Netherlands, in 2017. On Sunday, a statement from the group made from The Hague denied responsibility for the attack, saying that the group who claimed responsibility in the name of Ahvaziya were expelled from the organization in 2015.