Update 10.18pm:Terrorists launched attacks on Iran's parliament and the tomb of its revolutionary leader, Ayatollah Ruhollah Khomeini.
The Islamic State group claimed responsibility for the onslaught in which at least 12 people were killed and 40 wounded.
Earlier:Five suspects have been detained following the deadly dual attacks in Tehran that killed at least 12 people and wounded more than 40, the city's police chief said.
General Hossein Sajedinia told the semi-official ISNA news agency on Wednesday night that police are interrogating the suspects.
He did not elaborate, but said Tehran is safe and police and other security forces are deployed and closely monitoring the Iranian capital.
The attacks were claimed by the Islamic State group.
Earlier:Iran's powerful Revolutionary Guard has indirectly blamed Saudi Arabia for the twin attacks.
In a statement, it stopped short of alleging direct Saudi involvement but called it "meaningful" that the attacks took place about one week after US President Donald Trump travelled to Saudi Arabia and strongly asserted American support for Riyadh.
The statement said Saudi Arabia "constantly supports takfiri terrorists" including Islamic State, and the IS claim of responsibility "reveals their (Saudi Arabia's) hand in this barbaric action".
The statement concludes that the "spilled blood of the innocent will not remain unavenged".
Earlier: Gunmen and suicide bombers have attacked Iran’s parliament and the shrine of its revolutionary leader, killing at least 12 people and leaving dozens more injured.
The Islamic State group has said it was behind the attacks, marking the first time the Sunni extremists have taken responsibility for an assault in Shiite-majority Iran.
The attacks began when assailants armed with Kalashnikov rifles stormed the parliament building, starting a three-hour siege during which one of the attackers blew himself up inside while a session was in progress.
Deputy interior minister Mohammad Hossein Zolfaghari told Iran’s state TV the apparently male attackers wore women’s attire.
All four attackers were killed during the violence.
The IS group’s Aamaq news agency released a 24-second video purportedly shot inside the parliament building during the siege. The video, circulated online, shows a gunman and a lifeless body of a man lying on the ground next to a desk.
A voice on the video praises God and says in Arabic: "Do you think we will leave? We will remain, God willing." Another voice repeats the same words. The two appeared to be parroting a slogan used by IS spokesman Abu Mohammad al-Adnani, who was killed in Syria last year.
The militants are at war with Iranian-backed forces in Syria and Iraq, and view Shiites as apostates.
Witnesses reported seeing several police snipers on the rooftops of buildings around the parliament, while attackers were said to be shooting from the fourth floor of the parliament down at people in the streets below.
— TIMES NOW (@TimesNow) June 7, 2017
Police helicopters circled over the parliament building and all mobile phone lines from inside were disconnected. Politicians and reporters were ordered to remain in place inside the chamber during the siege.
Parliament speaker Ali Larijani called the attack a cowardly act, and added: "Iran is an active and effective pillar in the fight against terrorists and they want to damage it."
Soon after the parliament attack, a suicide bomber and other assailants targeted the shrine of Ayatollah Ruhollah Khomeini located just outside the capital.
Khomeini, who died in 1989, is a towering figure in Iran. He led the 1979 Islamic revolution that toppled the Western-backed shah and became Iran’s first supreme leader.
Mizan Online, an Iranian state-run news website, said 12 people were killed and 42 injured in the two attacks.
Update 12.15pm: It’s being reported that the Islamic State has published a video showing the attack on the Iranian parliament, which is thought to have killed at least seven people.
According to Reuters, the footage shows gunmen inside the building in Tehran, where it’s understood four people have also been taken hostage.
Iran’s deputy interior minister says ones of the attackers was shot dead while another detonated a suicide vest.
— Reuters (@Reuters) June 7, 2017
Earlier: A security guard has been killed and 12 other people injured in twin attacks on Iran’s parliament and the shrine of Ayatollah Ruhollah Khomeini.
Officials said the gun attack on the parliament building in the capital, Tehran, was still under way.
It was not immediately clear who was behind the attacks or if they were co-ordinated.
Iran's state TV said a security guard was killed and four other people injured in the attack on the shrine.
It said one of the assailants was killed by security guards and that a woman had been arrested.
It described the attackers as "terrorists" and said one carried out a suicide bombing, without providing further details.
State TV later said four attackers were involved in the parliament attack, and that eight people were wounded.
The semi-official ISNA news agency said all entrance and exit gates at parliament were closed and that politicians and reporters had been ordered to stay inside the chamber.