HASSAKEH, Syria/MOSCOW: As Daesh (ISIS) closes in on government-held areas of Syria’s Deir al-Zor, residents said they are terrified of falling victim to the mass killings for which the militants have become infamous.

The developments in eastern Syria came as Russia and Turkey carried out their first joint airstrikes against Daesh in the north.

In Deir al-Zor Wednesday, the militant group set tires ablaze to create a smokescreen from regime and Russian warplanes as fierce clashes gripped the city, the Syrian Observatory for Human Rights said.

Daesh launched a fierce assault Saturday to capture the government-held third of the city, as well as the adjacent military airport; 160 people have been killed.

Since then, Daesh has steadily advanced in a fresh assault on that part of the city, sparking fears among residents of widespread atrocities.

“Civilians in the city are terrified and anxious, afraid that Daesh will enter [government-held parts of] the city since they accuse us of being ‘regime thugs,’” Abu Nour said.

He spoke by phone from inside the city, roughly 1 kilometer from approaching Daesh forces.

As the group advanced on ancient city Palmyra in 2015, it killed dozens of civilians, accusing them of being regime loyalists, then staged mass executions of government troops in the city’s theater.

According to one activist group, Deir Ezzor 24, Daesh has already begun executing Syrian soldiers it took captive during the clashes in Deir al-Zor, “by driving over them with tanks.”

A medical source in the city told AFP more than 100 civilians had been wounded in the recent fighting, and some were taken to the Kurdish-majority city of Qamishli.

On the diplomatic front, key rebel group Ahrar al-Sham said Wednesday it would not take part in peace talks, organized by Russia, Turkey and Iran, in the Kazakh capital next week aimed at ending the war.Ahrar al-Sham, which counts thousands of fighters in central and northern Syria, said its decision was due to “the lack of implementation of the cease-fire” in force since Dec. 30 and ongoing Russian airstrikes over Syria.

Ahrar al-Sham cited “the regime’s offensive against our people in Wadi Barada,” an area 15 kilometers northwest of Damascus that is the capital’s main source of water, among its reasons for staying away from the talks. The Islamist faction was among the signatories of the cease-fire deal.

Ahrar al-Sham said however that it would support decisions taken by other rebel groups represented at the Astana talks if they were “in the interest of the nation.”

Regime and rebel figures are headed for Kazakhstan with diametrically opposed approaches to the aims of the talks.

Damascus has insisted it would seek a “comprehensive” political solution to the conflict, while rebels say they will focus solely on reinforcing the frail nationwide truce.

Iranian Foreign Minister Mohammad Javad Zarif Wednesday said Iran and Saudi Arabia should be able to work together to help end conflicts in Syria and Yemen, after successfully cooperating over Lebanon last year.

“I do not see any reason why Iran and Saudi Arabia should have hostile policies toward each other. We can in fact work together to put an end to miserable conditions of the people in Syria and Yemen and Bahrain and elsewhere in the region,” he said.

Meanwhile, Iranian officials said they were strongly opposed to Washington joining the talks. Turkey and Russia have however said the new U.S. administration of Donald Trump should be represented.

In northern Syria, the Russian military said Wednesday it has teamed up with Turkey to conduct joint airstrikes, coordinated with Damascus, against the Daesh stronghold of Al-Bab. It is the first acknowledgement of Russian cooperation in support of Turkey’s offensive in the area.

It is also the first incident of indirect coordination between the Turkish and the Syrian governments. Ankara has been calling for the ouster of President Bashar Assad and has supported the armed rebellion against him. Syrian officials have called Turkey’s operations on Syrian territories an “occupation.”

In a sign of a possible new ground for cooperation in the area, U.S. defense officials said Tuesday the U.S-led coalition have also carried out attacks against Daesh in the same area, in the province of Aleppo, at a time when Turkish troops have struggled there since November.