Update from ISNA News Agency says at least two people have been killed and eight wounded in the twin attacks at Iran's Parliament building and at the Khomeini's mausoleum in south Tehran said.

At least four people had entered via the western entrance of the mausoleum and opened fire, killing the gardener and wounding several people, according to the Fars news agency.

Fars also said a female suicide attacker blew herself up outside the shrine and published photos showing the explosion.

Four men armed with rifles and a pistol were reported to be inside the parliamentary complex, around 20 kilometres away in the centre of the city.

Tasnim news agency said one of the men had later left the building and was firing in the street, but was forced back inside by police fire.

News agencies ISNA and Fars had earlier said three people had been shot after the gunmen entered via the north entrance. A security guard has been shot dead.

The ILNA news agency said security forces were dismantling a bomb inside the Khomeini shrine and that firing was still going on around the site. It was not clear if the assailants had been able to enter the actual mausoleum. The city was on lockdown, with streets blocked and the metro closed, and journalists kept away from the shrine by police.