ISIS in Ramadi: Shiite militiamen mass to help retake city from Sunni militants

Thousands of Iran-backed militiamen were massing on Monday to help retake the city of Ramadi after ISIS captured the Anbar provincial capital in a stunning setback for Iraq's government.

At least 500 people have been killed in Ramadi while around 8,000 have fled, a spokesman for the governor of Anbar told NBC News.

"There have been executions in the streets of Ramadi," Muhanad Haimour said, describing how ISIS fighters used cars, bulldozers rigged with explosives and suicide bombers to overrun the city following a weeks-long fight for control.

"The situation in the city is absolutely terrible," Haimour added. "The city is in very bad shape."

Related: ISIS seizes control of major Iraqi city

The fall of Ramadi comes despite the support of U.S.-led airstrikes against ISIS and just weeks after Iraq's army and Shiite militias recaptured Tikrit from the Sunni militants. Haimour said he believed fighters retreating from Tikrit had "set their sights on Ramadi" — but expressed certainty the provincial capital wouldn't stay in ISIS' hands for long.

Iraqi forces reportedly fled their posts as ISIS advanced, in scenes reminiscent of when the militants overran key cities last summer in a rapid-fire assault to consolidate territory.

When asked if the fall of Ramadi signaled a failure on the part of Iraq's central government, Haimour stressed that Prime Minister Haider al-Abadi had "been doing everything he can" and "dealing with a lot."

"It is obviously a failure no matter how you look at it," Haimour conceded. "But we believe the security forces will be able to regroup."

"We are confident that we will regain control of the city in the days to come," Haimour added, echoing U.S. Secretary of State John Kerry, who said from Seoul he was "absolutely confident" Ramadi's takeover would be "reversed" in the coming days as forces are redeployed to the city.

Al-Abadi over the weekend ordered Shiite militias to prepare to go into Anbar Province, despite widespread concerns their presence could trigger sectarian violence.

One senior Iraqi security official told NBC News that around 3,000 of the Iran-backed fighters — from armed Shiite groups including the Al-Khurasani Platoons, The Chosen Ones Movement and Badr Forces — were arriving in Ramadi on Monday with more due to deploy in the coming 48 hours.

The senior official also said that Iran's Defense Minister Brig. Gen. Hossein Dehqan had arrived in Baghdad for talks to discuss the security situation — underscoring Tehran's vested interest and role as regional Shiite powerhouse in beating back the Sunni ISIS fighters.

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Haimour would not say how many of the militiamen — known as the Popular Mobilization Forces — were being called up, but said their arrival will change the game.

While he acknowledged that "Ramadi is a very important city," Haimour said "no one" expects ISIS to survive in Iraq for long.

"We believe we are seeing the final chapter," he said. "Not a new beginning or a victory."

Iraq's Ambassador to the U.S. said his government was using "all available resources" in the fight against ISIS and working with coalition partners to contain the situation in Anbar province "before the ground assault begins to free our country."

"The war with ISIS is a marathon, not a sprint," Lukman Faily said on Twitter. "The battle for Ramadi will be decisive in Iraq's favor."

This story originally appeared on NBC News