An Iraqi fighter aims his gun to protect the military headquarters from an attack by Islamic State extremists in Ramadi. (AP)

Islamic State militants tightened their grip on Ramadi on Saturday as officials, police and residents accused the Sunni extremists of executing dozens of civilians and blowing up homes in the capital of Iraq’s largest province.

On Thursday, the insurgent group launched a brutal offensive involving car bombings and heavy shelling to seize Ramadi, which is about 80 miles west of Baghdad. The militants controlled most of the city by Friday afternoon, hoisting the group’s black flag over government buildings as pro-government forces retreated.

“They blew up the houses of the officers and [tribal] sheiks who fought them,” said Hamid Shandoukh, a Ramadi police colonel, speaking by telephone from the city’s Malaab area.

The attack is a significant setback to Iraq’s U.S.-backed government, which is waging a military campaign to retake territory that the Islamic State seized in sweeping advances last summer. The United States has assumed a prominent role in that effort, leading an international coalition that is conducting airstrikes against the extremist group in Iraq as well as in Syria.

Dozens of residents across Ramadi have been executed by Islamic State fighters, including women and children, according to residents and pro-government forces. “We don’t have precise figures, but we can say that dozens of them were shot by Daesh,” Shandoukh said, using the Arabic term for the group.

Iraqi family members prepare to leave their hometown of Ramadi, the capital of Anbar province. Islamic State militants seized the center of Ramadi in western Iraq and raised their black flag over the government compound, local officials said. (Uncredited/AP)

Police, counterterrorism forces and tribal fighters have retreated to Malaab and a nearby military command hub, where hundreds of them are surrounded by Islamic State fighters. Police and local officials say that supply lines to the facility have been cut and that those on the inside are in desperate need of food as well as military reinforcements to defend against shelling and car bombings.

“We are calling on the government to provide food as well as military reinforcements to these areas that are besieged by Daesh,” said Suleiman Kubaysi, head of media relations for ­Anbar’s provincial council. He spoke by telephone from ­Baghdad.

Anbar capital is a key prize

Ramadi, capital of the largely Sunni province of Anbar, has been a stronghold of opposition to the Islamic State and its al-Qaeda precursor. A little less than a decade ago, the city’s residents were at the forefront of a U.S.-backed revolt by Sunni tribesmen against al-Qaeda.

Ramadi’s apparent fall is a major blow to U.S.-supported efforts by the government of Iraqi Prime Minister Haider al-Abadi to form another Sunni force against the Islamic State, said Hassan Hassan, an Abu Dhabi-based Middle East analyst and co-author of “ISIS: Inside the Army of Terror.” ISIS and ISIL are acronyms for the Islamic State.

“This is a heavy blow to the idea of getting Iraq’s Sunnis to rise up to fight ISIS,” he said, adding that Ramadi is “vital” to such an effort. Despite capturing most of Anbar last summer, the Islamic State had been unable to conquer Ramadi in repeated attempts that included an attack last month. In that assault, militants gained control of northern areas of the city.

Now, with its capture of most of the city, the Islamic State has received a major morale boost after losing significant territory recently to Iraqi forces, including the city of Tikrit, Hassan said. “This is important for ISIS in terms of bouncing back and reclaiming momentum,” he said.

During a telephone call Friday that highlights concern in Washington about the Ramadi attacks, Vice President Biden promised Abadi deliveries of heavy weapons, the White House said.

During a television interview Saturday morning, an Iraqi military spokesman, Brig. Gen. Saad Maan, said that troop reinforcements had been sent to the city. “Painful” airstrikes from the U.S.-managed coalition also inflicted damage on the Islamic State, he said, without giving details of the military support.

Kubaysi, the provincial councilman, said a convoy of several dozen military vehicles carrying soldiers and counterterrorism forces arrived at the Malaab area from Baghdad on Saturday afternoon. But the additional troops have not engaged in fighting, he said.

“They are waiting for more reinforcements to arrive from Baghdad before they fight,” he said.

Falih al-Essawi, deputy head of Anbar’s provincial council, said that several members of Iraq’s SWAT team arrived Friday night but that the city is still waiting for special forces units to join the fight.

Coalition airstrikes were targeting militants in the city, Essawi said. He added that officials put the preliminary death toll from recent fighting in Ramadi at more than 500 people, including police, soldiers and civilians.

Unconfirmed video posted on social media by the Islamic State shows the group’s fighters capturing the main hospital in downtown Ramadi. In photographs posted online, the group also claims to have seized rocket-propelled grenades, boxes of ammunition and vehicles from police and military installations in the city. The group also posted pictures of what it says are executions in the city.

Informants in ‘sleeper cells’

Col. Eissa al-Alwani of the Ramadi police said the pro-
government forces besieged in the city’s military operations compound were quickly running out of ammunition. The Islamic State is targeting the compound, where three of Alwani’s brothers are trapped, with heavy shelling and car bombs, he said.

In other parts of the city, he said, Islamic State “sleeper cells” have begun informing the group’s fighters about residents who joined the police and military. Those who were identified as government collaborators, including families, are being executed and their homes are being blown up, Alwani said.

“Yesterday, they killed 20 of my cousins, and they blew up my house in Albu Alwan,” he said by telephone from the Malaab area.

He added: “There will be a massacre if there is no help.”

In the battle for Tikrit, about 120 miles north of Baghdad, pro-Iran Shiite militias proved decisive in overwhelming Islamic State forces.

But those militias have not participated in the fight in Anbar, in part over fear of stoking sectarian tensions with the area’s largely Sunni residents. The Islamic State took control of most of Anbar by capitalizing on Sunni grievances with the Shiite-led government in Baghdad.