Attackers have mounted simultaneous gun and suicide bomb assaults on Iran’s parliament building and the tomb of the republic’s revolutionary founder, in one of the most audacious assaults to hit Tehran in decades.

At least 12 people were killed and dozens more injured in the twin assaults on the Iranian capital, state media reported. A third attack was foiled, Iran’s Intelligence Ministry said.

ISIS issued a swift claim of responsibility. Its media wing, Amaq, claimed “fighters with the Islamic State” carried out the attack, but did not offer evidence.

The attack was highly unusual: Until now, Tehran has been a safe city for its residents as Iran has largely escaped the regular attacks launched against other participants in neighboring Syria’s civil war.