A mob attacked the U.S. Embassy in Baghdad on Tuesday, prompting some embassy staff to evacuate. The mob was angered by last weekend’s U.S. airstrikes against the Iran-backed Shiite militia Kataib Hezbollah (KH), which killed an American civilian contractor in a rocket attack last week.

President Donald Trump said on Tuesday morning that Iran “orchestrated” the embassy attack and would be “held fully responsible.”

Iran killed an American contractor, wounding many. We strongly responded, and always will. Now Iran is orchestrating an attack on the U.S. Embassy in Iraq. They will be held fully responsible. In addition, we expect Iraq to use its forces to protect the Embassy, and so notified! — Donald J. Trump (@realDonaldTrump) December 31, 2019

The mob grew into thousands of people, led by openly identified KH supporters, some of them wearing uniforms and waving militia flags. The attack began after a funeral service for the 25 KH fighters killed by the U.S. airstrikes. Demonstrators marched through the streets of Baghdad carrying photos of the slain KH members and Iraq’s top Shiite cleric, Grand Ayatollah Ali Sistani, who condemned the American airstrikes.

KH vowed to seek revenge for the airstrikes on Monday. Both KH and the Iranian military unit that supports it, the Islamic Revolutionary Guard Corps (IRGC), have been designated as terrorist organizations by the U.S. government. The government of Saudi Arabia also described KH as one of several “terrorist militias supported by the Iranian establishment” in remarks on Tuesday condemning the assault on the U.S. embassy.

The attackers were able to smash open a gate and push into the embassy compound, lighting fires, smashing cameras, and painting messages such as “Closed in the name of resistance” on the walls. Gunshots were reportedly heard near the embassy, while tear gas and stun grenades were deployed by its defenders.

A uniformed militia fighter on the scene in Baghdad told Kurdish news service Rudaw that attacks were also planned against the U.S. consulates in Erbil and Basra, with the goal of destroying the consulates and killing everyone inside.

“This is a letter to Trump and the American embassy in Baghdad and its consulate in Erbil and in Basra,” he said. “Those who have attacked our forces and our Jihadi brothers… God willing, if this fire reaches inside of the embassy, we will not spare a single employee. We are the children of the martyrs and this is our statement, death to America.”

Several militia commanders loyal to Iran were spotted in the mob, including Hadi al-Amiri, head of the state-sponsored Popular Mobilization Units (PMU) umbrella organization for paramilitary groups. At least one sitting member of the Iraqi parliament also participated in the attack.

Iraqi government Member of Parliament Hasan Salem participated in the attack against the U.S Embassy in #Baghdad #Iraq , he claims this is the end for U.S and allies including Saudi Arabia ,Israel and UAE. pic.twitter.com/kgjyk5dir5 — Steven nabil (@thestevennabil) December 31, 2019

Iran and its terrorist proxies in Iraq were not without support from the Iraqi government, which is teetering on the verge of collapse after months of protests from Iraqis angered by Iranian influence over their country. Outgoing Prime Minister Adel Abdul-Mahdi, who technically resigned in late November but has not yet been replaced, denounced the U.S. airstrikes against Kataib Hezbollah as “sinful,” the same term used by Grand Ayatollah Sistani.

“The Iraqi government condemns this act and considers it a violation of its sovereignty and a grave violation of the coalition forces’ rules of action, including the American forces, by carrying out operations without the approval of the Iraqi government,” said a statement issued by Abdul-Mahdi’s office on Monday.

Observers in Baghdad found it suspicious that the embassy attackers were able to penetrate the “Green Zone” safe area without resistance from Iraqi security forces, who usually repel angry crowds that attempt to enter the area:

A sight I didn't expect this morning when we set out to cover a funeral processions. Thousands of PMF marching through checkpoint leading to US embassy, with no effort by Iraqi sec forces to stop them pic.twitter.com/FRyL2L8vhc — Simona Foltyn (@SimonaFoltyn) December 31, 2019

Iraqi Interior Minister Yassine al-Yasseri appeared at the embassy to inspect the scene but made no apparent effort to halt the attack. After a few hours, a small group of Iraqi soldiers arrived in armored vehicles and urged the mob to move back from the embassy, without taking action to disperse the protest. Iraqi riot police reportedly attempted to reach the embassy but were blocked by the mob.

Prime Minister Abdul-Mahdi belatedly warned against attacks on foreign embassies on Tuesday and asked the demonstrators to leave, promising that violence and vandalism would be punished.

Although early reports said U.S. Ambassador Matthew Tueller was evacuated from the embassy during the attack, ABC News was told on Tuesday that Tueller was on leave and was not in Iraq at the time of the assault.