ISIS on Wednesday claimed responsibility for a pair of attacks in Tehran that included suicide bombers and teams of gunmen who stormed Iran's parliament and the nearby shrine of Ayatollah Ruhollah Khomeini.
Two security guards were killed and 30 other people were injured in the rare twin attacks, with the siege at the legislature still underway.
SITE Intel Group reported that this is the first attack orchestrated by ISIS in the country.
One of the attackers blew himself up inside the parliament building, 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 and four people wounded 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.
--The Associated Press contributed to this report.