Islamic State attacked an Iraqi police checkpoint near the southern city of Najaf on Sunday, killing seven policemen as government forces in the north made more gains against the militants in Mosul, their last major stronghold in the country.

The Najaf attack, which involved gunmen and a suicide car bomb, followed blasts a day earlier in Baghdad that left 29 people dead, a reminder of Islamic State’s continued ability to operate away from territory under its control.

The recapture of Mosul would probably spell the end for the group’s self-styled caliphate in it areas seized in 2014, but the militants would still be capable of fighting a guerrilla-style insurgency in Iraq, and plotting or inspiring attacks on the West.

Since the U.S.-backed offensive began on Oct. 17, elite forces have retaken a quarter of Mosul in the biggest ground operation in Iraq since the 2003 U.S.-led invasion that toppled Saddam Hussein. Prime Minister Haider al-Abadi has said the group would be driven out of the country by April.

The second phase of the campaign launched on Thursday following weeks of deadlock has pushed Islamic State out of several more areas despite fierce resistance.

The fourth day of the renewed push saw incremental advances on the eastern and southeastern fronts.

A military statement said the counter-terrorism forces had retaken part of Karama district.

A federal police officer said Iraqi forces had taken near total control of Intisar and Siha neighbourhoods, and were clearing Salam.

“For the fourth day in a row, federal police units supported by the army are on the offensive,” he told Reuters at a forward base in Intisar.

The attack near Najaf, 500 km (310 mile) south of Mosul, happened when two vehicles travelling through the desert were stopped at a police checkpoint around al-Qadisiya town, local police sources said.

The driver detonated an explosive load and the second vehicle fled. Police pursued it and killed the two militants inside.

In a statement distributed online by supporters, Islamic State claimed responsibility for the attack, which also wounded 17 people including civilians. It said four gunmen had opened fire before detonating explosive vests and then a fifth assailant launched a suicide car bomb.

It was not immediately possible to reconcile those accounts.

FLEEING CIVILIANS

Although the militants are vastly outnumbered in Mosul, they have embedded themselves among residents, hindering Iraqi forces who are trying to avoid civilian casualties. Despite food and water shortages, most civilians have stayed in their homes rather than fleeing as had been expected.

Thousands more people have fled their homes since the military’s new push began, many under the cover of darkness to avoid detection by Islamic State.

Families leaving Mithaq district on Sunday had to climb over earthen berms the military has built across roads to block car bombs.

One resident reached by phone in eastern Mosul said he had never seen such heavy bombardment. Several civilians were wounded when a mortar fell in his street, but they could not be ferried to the hospital on the western side of the city because air strikes have taken all the bridges out of service.

“One of them is my friend. His stomach is bleeding badly. We found a doctor in the neighbourhood to treat him but I fear he will die if he stays like this for long,” he said.

A resident of Karama district said Islamic State had begun forcing residents out of some areas, burning the cars of residents who refused to move.

“They want to clear out the neighbourhood before the Iraqi forces enter,” he said.

Christians in Baghdad celebrated Christmas on Sunday in a heightened state of fear after deadly attacks on Christian-owned shops that sell alcohol.

Two shops next door to each other were riddled with bullet holes and spattered with blood after gunmen opened fire late on Friday in Baghdad’s Ghadeer neighbourhood. Police and medical sources said three people were killed and four wounded.

Local activists gave a higher death toll. Rayan al-Kildani, commander of Babiliyon Brigades, a group of Christian volunteers formed to fight Islamic State militants, said eight Christians and one member of the Yazidi sect had been killed in the attack.

“What a bloody gift they gave us for Christmas,” Joseph Warda, a Christian human rights activist, told Reuters.

Maria Polos, a retired schoolteacher in the district where the attack took place, said she and other Christians were afraid to celebrate the holiday in public.

“We fear getting killed like those in the alcohol shops,” she said. “We feel we’re aliens in this country.”

The sale of alcohol is generally shunned among Iraq’s Shi’ite and Sunni Muslims, and Christian-run shops that sell it were frequently targeted by militants from both Muslim sects during Iraq’s years of sectarian civil war.

This year, government forces have been pushing fighters from the militant group Islamic State out of parts of northern Iraq where it had banned the practice of any religion apart from Sunni Islam.

Areas once held by the group have seen their first Christmas services since 2013, and many Christians there have sounded more hopeful than they have for years about the fate of communities that date back to biblical times.

In Baghdad, the capital which is firmly controlled by the Iraqi government and security forces dominated by Iraq’s Shi’ite majority, Christians celebrate Christmas in churches decorated for the holiday. But many say they still live in fear, and do not feel the authorities protect them adequately.

Although the identities of the attackers who struck the liquor store were not known, the area is predominantly Shi’ite and Shi’ite groups have firm control of security. Warda, the human rights activist, said militants from any sect that attacked civilians in the name of religion were “no better than Islamic State”.

Vian Dakhil, a lawmaker from the ancient Yazidi sect, whose members were targeted in northern Iraq by Islamic State for what Western countries described as genocide, also said one Yazidi and eight Christians were killed in the Baghdad attacks.

“The criminals should be brought to justice as soon as possible so that their punishment serves as an example to those who dare kill civilians in the name of religion,” Dakhil said on her Twitter page.