President Rouhani calls for unity to fight terror, but Revolutionary Guard vows ‘revenge’ after attack killed 12 people.

Armed attackers and suicide bombers have targeted two of the most important national symbols of Iran, leaving at least 12 people dead and throwing the country into a state of unease, amid already heightened regional tensions.

Wednesday’s attack on the national parliament and the shrine of the Islamic Republic’s founder Ayatollah Ruhollah Khomeini were “unprecedented” actions against state institutions in recent years, and it could reverberate across the Middle East, said Reza Khaasteh, a journalist of the Tehran-based Iran Front Page.

“We did not have any similar attack in Iran for a long time,” Khaasteh told Al Jazeera. “This one is like those that happened in Europe.”

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“If links to foreign sources are found, it can be an escalation,” he said.

The armed group, Islamic State of Iraq and the Levant (ISIL, also known as ISIS), said its fighters carried out the attack.

All four suspects involved in the parliament siege are dead, and the three others at the Khomeini shrine were killed.

Al Jazeera could not independently confirm the claim that they were ISIL fighters.

Until the attack on Wednesday, Iran has been fighting against ISIL in Iraq and Syria. However, during Ramadan in 2016, the Iranian government reported that it foiled a major ISIL plot within the country.

“There were numerous attempts by ISIL elements to enter Iran for terrorist operations. But all of them have been diffused. This time, we do not know what will happen,” Khaasteh said.

Following the attack, Iran’s Revolutionary Guard vowed “revenge” against ISIL and its supporters, even as the country’s Supreme Leader Ayatollah Ali Khamenei said the “firecrackers” would not affect “the will of the nation”.

After calling an emergency security meeting, President Hassan Rouhani called on world leaders to unite to combat “extremism”.

During the holy month of Ramadan in 2016, Iran said it also foiled an attack in the country [Reuters]

‘Cowardly attackers’

But the attack, which left at least 39 people injured, was a clear assault on both secular and religious pillars of the Iranian society, said Amir Havasi, a journalist at Tehran’s leading English-language financial newspaper.

“The parliament is a symbol of Iran’s struggle against monarchy and enforcing the Constitution, and the [Khomeini] mausoleum is a symbol of the revolution’s triumph,” Havasi told Al Jazeera.

Sitting next to Tehran’s largest mosque in the central part of the city, the pyramid-like structure known as Baharestan, houses the 290-seat unicameral parliament, or the Majlis.

The actual attack took place in an adjoining building, where the offices of the parliament members are located. Reports said the attackers failed to reach the main hall.

Images and videos posted online showed shots flying out from the upper floors of the building, as special forces and police fought off the attackers for several hours.

Afterwards, Iran’s Parliament Speaker Ali Larijani denounced the “cowardly attackers”, even as he downplayed it as a “minor incident”.

“Iran is an active and effective hub for combating terrorism, and terrorists wish to undermine such activities,” he was quoted by Mehr News Agency as saying.

The other attack hit the Khomeini shrine, which houses the tomb of the revered architect of the 1979 Iranian Revolution and the country’s first supreme leader, who died in 1989.

The complex, located about 30km south of the city and halfway to Tehran’s main international airport, attracts hundreds of thousands of pilgrims every year. It was also hit by a suicide attack in 2009.

In the latest incident, one of the attackers was caught on phone camera blowing up an explosive, as shots rang out and visitors ran for protection.

It was unclear if all the attackers at the shrine were also killed. According to an earlier report, two attackers were “arrested”.

Authorities also said it prevented a third attack, but did not disclose the location.

‘Audacious attack’

Javad Zarif, Rouhani’s foreign minister, who is in Ankara to meet Turkish leaders, condemned the attack saying “terrorism” is a problem in the Middle East and the rest of the world.

“The region is witnessing worrisome developments for us,” he told reporters.

Out in the streets of Tehran, political analyst Amir Havasi told Al Jazeera it was back to normal after the attack.

“From what I have seen so far, ordinary life is continuing. People are still taking the subway, using public transportation,” he said.

Still, the “audacious attack” on Wednesday raises questions about security in the Iranian capital, which is known as a “safe city”, said Al Jazeera’s Andrew Simmons, who has extensively covered Iran, including the latest presidential election.

“Here, we have a credibly well-planned attack,” he said. “Why did these people slipped through the net?”

“Tehran is always been known as a safe city. Its people are not used to this sort of attack. What the government faces right now is a security problem.”

He said it could result in the newly re-elected and moderate president taking a harder line on the issue of security and surveillance.

“Rouhani thought the economy is his biggest problem. Now security could well end up at the top of his [agenda].”