Updated

Tehran, Jun 7 (IANS): At least eight people were killed on Wednesday in the first terror attack claimed by the Islamic State in Iran, with killers acting in coordination targeting the Parliament House and Ayatollah Khomeini's mausoleum in Tehran's heart.

Details of the twin attacks remained sketchy even several hours later. Lawmaker Tayebeh Siavoshi told Efe news that the situation was "very confusing and sensitive" and denied media reports that the situation was under control.

The Islamic State, a Sunni jihadist group, claimed responsibility for both attacks in the Shia majority nation, Efe news reported.

In the first incident, four gunmen armed with assault rifles forced their way into Parliament when it was in session and opened fire at security guards and visitors, leaving at least seven dead, Efe said.

But the BBC reported that only one security guard was killed in Parliament.

Two hours later, one of the Parliament attackers blew himself up, the state-owned television reported.

As the attack unfolded, security forces hurriedly closed the doors of Parliament and neither the lawmakers nor journalists were allowed to leave.

Efe quoted the Iranian Students News Agency (ISNA) as saying that one of the assailants was arrested while the other three remained holed up inside.

Minutes after the Parliament attack began, two people blew themselves up at the mausoleum of Khomeini, the founder of the Islamic state, killing an employee and wounding four visitors, Efe reported.

Two other terrorists at the mausoleum, one of them a woman, were arrested.

Within hours, the Islamic State terror group claimed responsibility for both the attacks through its affiliated news agency Amaq.

The BBC said this was the most serious terrorist incident in Tehran since the early years of the Islamic revolution of 1979 led by Khomeini.

The Islamic State has no following in Iran but has stepped up its Farsi language propaganda in a bid to woo the country's Sunni minority.