Iran's infamous Revolutionary Guards accused Saudi Arabia of being behind the twin terrorist attacks in Tehran, which killed 12 and left at least 39 injured, and have vowed "revenge."

Earlier in the day, a group of four people in women's clothes opened fire in the building of the Iranian Parliament, with a subsequent explosion. Another attack involving an explosion took place near the Imam Khomeini shrine. One of the perpetrators of the attack was detained and the rest were executed.

"This terrorist attack happened only a week after the meeting between the U.S. president (Donald Trump) and the (Saudi) backward leaders who support terrorists. The fact that Islamic State has claimed responsibility proves that they were involved in the brutal attack," said the statement, published by Iranian media.

What is notable is that ISIS already claimed responsibility for the attack, so Iran is explicitly accusing Saudi Arabia of supporting the Islamic State.