ISIS claimed its first attack in Iran, as suicide bombers and gunmen struck at the heart of the country's political and religious establishment.
Four attackers wearing women's clothing entered the Parliament building in Teheran and gunmen attacked the shrine of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini, to the south of the city yesterday morning.
Twelve people were killed and 42 injured in the simultaneous attacks, state-run Press TV reported. The Fars news agency said the two incidents, which lasted for several hours, were over.
The Sunni extremist group Islamic State in Iraq and Syria (ISIS) claimed both attacks using its Amaq News Agency, saying they were carried out by its fighters and were its first in Iran - the Middle East's Shi'ite power.
The rare violence in the capital comes as Iranian security forces and allied militias are involved in offensives against ISIS and other militant groups in both Syria and Iraq.
"The terrorists targeted the shrine of the founder of the regime and the beating heart of the people's leadership," Mr Hesamodin Ashena, an adviser to President Hassan Rouhani, said on Twitter.
The militants struck at a time of escalating tension between Iran and Saudi Arabia, the Middle East's pre-eminent Sunni power. Last month, US President Donald Trump gathered Sunni leaders in Riyadh in an effort to isolate Iran over its links to regional militants.
SEE TOP OF THE NEWS: Gunmen posed as women to attack key Iran targets