Attackers raided Iran's parliament and opened fire at the Mausoleum of Ayatollah Khomeini a few kilometres south of the capital, in near simultaneous assaults that killed at 13 people, according to Iranian media.
Three assailants, one with a pistol and two with AK-47 assault rifles, carried out the attack in central Tehran, an MP told state television.
Another MP said one of the assailants was surrounded by security forces and all the doors to the building had been closed, ISNA news agency reported.
The attackers killed 13 people and wounded 43 others.
Iran's deputy interior minister said security forces had surrounded the attackers who were dressed as women.
"One of the attackers in the parliament was shot dead, and one detonated a suicide vest," he said.
Around half an hour later, an attacker opened fire at the Mausoleum of Ayatollah Khomeini, injuring several members of the public, Iran's English-language Press TV said.
State news agency IRNA quoted an official at the mausoleum as saying the attacker had set off a suicide bomb after shooting at people.
Ayatollah Ruhollah Khomeini launched the Islamic revolution in 1979.
Iranian TV said parliament had resumed, and broadcast footage of what it said was the opening session proceeding normally.
State broadcaster IRIB reported that the shooting incident at the Iranian parliament was over and all four assailants were dead.
"The security forces are checking for bombs and clearing the building," IRIB said.
The so-called Islamic State group said it was behind the attacks, the group's propaganda agency AMAQ said.
