A photo being widely shared by Iranian media outlets purports to show a suicide vest recovered from inside the parliament building after the attack.
Some reports say it was successfully defused by special forces on the scene.
- Copyright: EPA
If you're just joining us, here's a brief run-down of events this morning:
- News initially broke of gunfire at Iran's parliament building this morning, injuring at least one guard
- Minutes later, it emerged that a simultaneous attack - a suicide bomb - had taken place at the tomb of the founder of modern Iran
- Gunfire continued in and around parliament over the next few hours, while MPs continued scheduled sessions in another part of the complex
- Rumours spreading on social media of a hostage situation were denied by officials
- Special forces eventually surrounded and killed all four known attackers at the parliament building
- At the mausoleum, press reports suggest that three surviving suspects were arrested after the fourth, a lone female suicide bomber, detonated her vest
- At least 12 people were killed and many more injured in both attacks
The latest report from the IRNA confirmed the earlier news that "one female suicide assailant" detonated a bomb outside the mausoleum.
Doubt was cast on the report of a female suicide bomber after it emerged the parliament attackers had dressed as women to gain entry.
According to Iranian English-language Press TV, three women and one man were involved in the attack at the Ayatollah Khomeini mausoleum.
The TV outlet had earlier reported that three surviving suspects at the mausoleum had been arrested - the fourth is believed to be the suicide attacker.
Iranian officials are now saying there were up to 12 fatalities and dozens more injured in Wednesday's attacks, various media sources report.
Fars news agency has said that all four attackers at the parliament building have now been killed by security forces, and the attack is "over".
At the second location, the mausoleum, some reports have said the situation is calm - but it is not yet clear if all attackers are accounted for.
- Copyright: ReutersCopyright: ReutersCopyright: Reuters
State news agency IRNA says two people have died in hospital, out of a total of 38 injured.
It is not clear if that number includes a parliamentary guard who was earlier reported killed.
The news agency quoted health ministry official Abbass Zarenejad as saying the remaining injured were being treated in four different hospitals.
Iran's health minister, Seyyed Hassan Hashemi, visited the victims, the report said.
This is the most serious terrorist violence in Tehran since the turbulent early years after the 1979 Islamic Revolution.
It will come as a huge shock to ordinary Iranians, who have got used to living in a country which is generally far more stable and safer than most of its neighbours.
Iranian intelligence services say a number of people have been arrested, including what they say is a team planning a third attack in the capital this morning.
It’s not clear at this stage who was behind the violence but so-called Islamic State (IS) has claimed responsibility. If confirmed this will be a first.
Despite Iran’s active involvement in fighting IS in both Iraq and Syria the group has so far not carried out any attacks inside Iran, and appears to have little support in this predominantly Shia country.
However in recent months the group has stepped up its Farsi-language propaganda efforts – targeting Iran’s restive Sunni minority, and the Iranian intelligence agencies claim to have foiled an number of IS-inspired plots.
Iran has announced a nationwide state of emergency in response to the attacks on Wednesday, IRTV1 quotes the deputy interior minister for security affairs as saying.
"All sites identified as possible targets for these groups have been secured," Hossein Zolfaghari told the channel, adding that he believed the incident at parliament would be over "in the next few hours".
He also said the attackers entered the parliament's side building dressed as women.
A correspondent for Iran's IRIB broadcaster, who is stationed outside the Khomeini mausoleum, says the situation there is calm.
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The Islamic State group (IS) has issued a video it claims was filmed by one of the attackers inside Iran’s parliament. The video was released by the group’s news outlet Amaq on the messaging app Telegram.
In the 24-second video, one of the alleged attackers (out of shot) appears to fire his weapon twice at a man lying motionless on the floor.
The footage has not been independently verified.
Iran's deputy interior minister says the attackers who entered parliament were dressed as women, according to Tasnim news agency.
One of them was shot dead, the other detonated a suicide vest, he added.
Photos show smoke outside Iran's parliament.
It was earlier reported by state media that an attacker had detonated a suicide vest at the building.Copyright: EPA
Iran's state news agency IRNA quoted the speaker of the parliament, Ali Larijani, downplaying the attack today.
He said “some coward terrorists" had infiltrated the building, but "were seriously confronted".“This is a minor issue but reveals that the terrorists pursue troublemaking,” he said.“Iran is particularly the active and effective hub of fighting against terrorism and they want to damage this trend.”
Richard Haass, the president of the Council of Foreign Relations and a former top diplomat under George W Bush, has some advice for US President Donald Trump:
Iranian lawmaker Mojtaba Zonnour says security forces have the streets near Iran’s parliament “under full control” but are still trying to control the situation inside the building, reports Mehr news agency.
“The security forces want to take the attackers alive so that they can find out who is behind the incident,” Zonnour told Mehr.
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So-called Islamic State (IS) has this year released a number of propaganda pieces focused on inciting attacks inside Iran.
IS's weekly Arabic-language newspaper al-Naba featured front page editorials in February and May urging Iran's Sunni minority to strike government and religious sites inside the country.
An IS documentary-style video in March featured militants who were introduced as Iranian fighters in IS ranks based in Iraq.
Speaking in Farsi, they denounced the Iranian government and the religious establishment, including the country's current spiritual leader Ayatollah Ali Khamenei.
By mounting a successful attack, IS could claim a major coup against a traditional foe that other Sunni jihadist groups, including its rival al-Qaeda, have failed to target in the past.
Press TV, meanwhile, has posted another video of continued shooting in the area: