The Islamic State group claimed a pair of attacks Wednesday on Iran's parliament and the shrine of Ayatollah Ruhollah Khomeini, which have killed two security guards and wounded more than 30 people, with the siege at the legislature still underway.
It marks the first attack in Iran claimed by the extremist group, which is at war with Iranian-backed forces in Syria and Iraq. In a message posted through its Aamaq News Agency, the IS group claimed its fighters were behind the assaults.
The group often claims attacks around the world, even when links to the group cannot be confirmed and appear dubious. Iranian security officials have not said who is behind the attacks.
Sunni extremists, including the IS, despise Shiite-majority Iran. Iran has also come under attack in the past by Arab insurgents.
The unusual attacks in Iran prompted the Interior Ministry to call for an urgent security meeting, according to the state-run IRNA news agency.
Assailants stormed the parliament building and one of the attackers blew himself up inside, where a session had been in progress, according to a statement carried by Iran's state TV. It quoted lawmaker Elias Hazrati as saying the attackers were armed with Kalashnikov assault rifles.
An Associated Press reporter saw several police snipers on the rooftops of buildings around the parliament. Shops in the area were shuttered, and gunfire could be heard. Witnesses said the attackers were shooting from the fourth floor of the parliament building down at people in the streets below.
"I was passing by one of the streets. I thought that children were playing with fireworks, but I realized people are hiding and lying down on the streets," Ebrahim Ghanimi, who was around the parliament building when the assailants stormed in, told The Associated Press. "With the help of a taxi driver, I reached a nearby alley."
Police helicopters circled over the parliament building and all mobile phone lines from inside were disconnected. The semi-official ISNA news agency said all entrance and exit gates at parliament were closed and that lawmakers and reporters were ordered to remain in place inside the chamber.
State TV reported four attackers are involved in the parliament attack, and said eight people were wounded.
Iran's official state broadcaster said a security guard was killed in the shrine attack. It said one of the attackers at the shrine was killed by security guards and that a woman was arrested. It described the shrine attackers as "terrorists" and said one carried out a suicide bombing, without providing further details.
In addition to being lethal, the attack on the shrine of Khomeini is symbolically stunning. As Iran's first Supreme Leader, Khomeini is a towering figure in the country and was its revolutionary leader in the 1979 ouster of the shah.
An Associated Press reporter saw security forces, some uniformed and others in plainclothes, around the large and ornate shrine located just outside the capital.