The deceased is reported to be a guard of the parliament.
Iranian media give different information on the number of attackers, varying from one to four people.
One of the attackers. Photo: Tasnim News Agency
According to lawmaker Mehdi Kiaee, the situation is under control inside the parliament, while security forces are working to restore calm there.
Tehran MP Elias Hazrati has said that the assailants were armed with two Kalashnikovs and a handgun.
The national identity of the attackers and their motives are unknown so far.
Later, Tasnim News Agency reported on its Twitter page about seven dead in the attack on Iran's parliament.
"Unconfirmed reports say seven people martyred in Iran's parliament shooting spree, four taken hostage," the message reads.