Saudi Arabia's mass execution of 47 prisoners — including prominent Shiite cleric Nimr al-Nimr — triggered unrest across the Middle East on Saturday, particularly in Iran, where protesters stormed and ransacked the Saudi embassy in Tehran.

Photos and video footage posted on Twitter by Iranian journalist Sobhan Hassanvandshowed a mob of angry demonstrators smashing windows and setting fire to the Saudi diplomatic outpost in the Iranian capital.

Video shows protesters inside Saudi embassy in Tehran pic.twitter.com/DEmsNLI6ZG — Sobhan Hassanvand (@Hassanvand) January 2, 2016

VIDEO: 12:08 AM, seems molotov cocktail thrown at Saudi embassy building in Tehran, protest over al-Nimr execution pic.twitter.com/d6vFKPcD6R — Sobhan Hassanvand (@Hassanvand) January 2, 2016

Protesters break into Saudi embassy building in Tehran pic.twitter.com/7wtBGpZuco — Sobhan Hassanvand (@Hassanvand) January 2, 2016

Saudi Arabia flag brought down at embassy in Tehran pic.twitter.com/7ptL0gV0ZF — Sobhan Hassanvand (@Hassanvand) January 2, 2016

Hassanvand later reported that police had successfully dispersed the protesters, and that firefighters were attempting to put out the fire at the embassy.

Earlier in the day, Iran's supreme leader Ali Khamenei posted a picture on his website comparing Islamic State militants to Saudi officials, suggesting that there is no difference in the way they handle their critics.

Iraqi Prime Minister Haider al-Abadi also condemned the executions. "I'm shocked & saddened at Sheikh Nimr's execution by Saudi authorities," he wrote on Twitter. "Peaceful opposition is a fundamental right. Repression does not last."

A spokesman for Iran's Foreign Ministry also condemned the executions, accusing the Saudis of hypocrisy. "The Saudi government supports terrorists and takfiri [radical Sunni] extremists, while executing and suppressing critics inside the country," the spokesman said.

Shiite Muslims also marched through the Qatif district of Saudi Arabia's Eastern province chanting "down with the Al Saud," the name of the Saudi royal family.

Meanwhile, protesters in Indian-controlled Kashmir, Pakistan, Iran, and Bahrain also took to the streets. Protesters in Mashhad, Iran, gathered outside the Saudi consulate building. Photos shared on Twitter suggest that demonstrators scaled the fence surrounding the consulate and removed the Saudi flag flying above it. Unconfirmed reports on social media said that protesters also torched the building.

Unsurprisingly, Iran's condemnation of the executions has rankled Saudi officials. A statement on the Saudi Press Agency's website says that the Ministry of Foreign of Affairs "summoned" the Iranian ambassador to the kingdom, and "handed him a strong-worded protest note" on the "aggressive" Iranian statements issued in response to the executions.

Moreover, the Saudi Foreign Ministry said it held the Iranian government "completely responsible" for the protection of the Saudi embassy in Tehran and the consulate in Mashhad, "and the safety of all its personnel from any hostile actions."

Demonstrations in Bahrain, a Sunni-ruled kingdom allied to Saudi Arabia, escalated into violence as protesters carrying pictures of the slain cleric marched through towns, in some cases, clashing with police, who fired tear gas in retaliation.

Groups such as Reprieve and Human Rights Watch also condemned the executions. A joint statement by human rights groups across Europe and in Bahrain called on the international community "to intervene in order to prevent any further bloodshed."

They also described Nimr as "a peaceful reformist that espoused non-violence in his dissent against the government of Saudi Arabia."

Alison Meuse, NPR's Middle East correspondent reported on Saturday that the Shiite Islamist militant group Hezbollah condemned Nimr's execution. Hezbollah reportedly suggested that the United States had blood on its hands for its continued alliance with Saudi Arabia.

Moqrada al-Sadr, a prominent Iraqi cleric, also called for peaceful demonstrations in Iraq and beyond "so as to deter injustice and government terrorism in the future."

According to Reprieve, four of the executed prisoners, including Nimr, were arrested in 2012 and given the death sentence for engaging in anti-government protests.

According to Reprieve, Ali al-Ribh was 18 at the time of his arrest, and was charged with vandalism, participating in anti-government demonstrations, and organizing proceedings using his Blackberry. Mohammad Shioukh was 19 when he was arrested, and sentenced to death for writing anti-government graffiti and filming demonstrations with the intent to publish their content. A statement from Reprieve alleges that both Ribh and Shioukh were tortured while in custody.

The Minister of the Interior released a statement following the executions on Saturday and quoted the Koran. "The recompense of those who wage war against Allah and His Messenger and do mischief in the land is only that they shall be killed or crucified or their hands and their feet be cut off from opposite sides, or be exiled from the land."