At least 12 people were killed and 42 others wounded in coordinated attacks on Wednesday morning that struck two of Tehran’s most significant sites: the national Parliament Building and the Tomb of the former spiritual leader, the Ayatollah Khomeini. Iranian officials say they managed to foil a third attack.

The Islamic State (ISIS) was quick to claim credit for the attacks. ISIS released an online video filmed inside the parliament building while the attack was taking place.  The video shows a gunman standing over the bloody body of a dead man lying. A voice on the video praises God shouts in Arabic, “Allahu Akhbar (God is greater). Do you think we will leave? We will remain, Inshallah (God willing).” Another voice repeated the same words.

If the claim is true, this is the first time ISIS has targeted Iran. Iran claims to be the head of the Shiite branch of Islam, and as such, is at odds with ISIS, an extreme branch of Sunni Islam. Iran is also the sponsor of much of global terrorism.

According to reports, four gunmen entered Parliament building via a public entrance, dressed as women. The building was locked down by security forces and cell phone coverage was blocked. Despite security efforts, one attacker left the building an hour after the siege began, running around Tehran’s streets, firing shots at bystanders. The gunman returned to the building. At least one of the assailants blew themselves up on the fourth floor as other attackers continued shooting from the windows. Security forces killed all four assailants

At approximately the same time as the attack on Parliament began, two assailants entered the west wing of the Khomeini mausoleum ten miles to the south. The site is of major importance as a destination for tourists and religious pilgrims. According to local news agencies, at least one attacker, believed to have been a woman, detonated an explosive vest in the western entrance of the mausoleum. Another assailant reportedly committed suicide by swallowing a cyanide pill.