At least 24 people were killed and another 53 wounded Saturday when gunmen attacked a military parade in southwestern Iran, the country’s state-run media reports. The gunmen, who were disguised as members of the Islamic Revolutionary Guard Corps, are said to have targeted an area where military and police commanders were sitting at the parade in oil-rich Ahvaz. At least eight members of the Revolutionary Guard were among those killed, according to local reports. Iranian Foreign Minister Mohammad Javad Zarif has vowed that Iran will “respond swiftly and decisively” after the attack, which he said was carried out by “terrorists recruited, trained, armed & paid by a foreign regime.” Zarif blamed regional countries and their “U.S. masters” for the violence. The so-called Islamic State has claimed responsibility for the attack but provided no evidence.