Atareb and the countryside around it remain outside the control of the Syrian government, which says it wants to retake all of Syria after six years of civil war that has killed at least 400,000 people and displaced 11 million others - half the country's population.

The Britain-based Syrian Observatory for Human Rights said there were three strikes on a market in Atareb in the opposition-held countryside outside Aleppo on Monday. The monitor said three strikes hit the town s market, adding that five children were among the dead, as well as three policemen.

Footage on social media shows rubble on the streets and frightened people tending to and carrying away those injured in the attack. Three men helped one of those hit in the attack, his face drenched in blood and his features nearly completely obscured.

Syrian Observatory for Human Rights said fifty civilians including twenty children, have been killed in the ongoing heavy bombardment in Deir Ezzor province since late Friday night. Atareb is located in part of Aleppo province where Russia, Iran and Turkey designated a de-escalation zone earlier this year.

Since then, with Moscow s support the government has recaptured large swathes of territory from opposition forces. Though there has been a drop in violence in these zones, clashes have occurred. Syria's conflict evolved from a government crackdown on protests in 2011 to a devastating war that has drawn in world powers, including Russian Federation and a US-led global coalition.

Airstrikes on a busy market killed dozens of people in the rebel-held town of Atareb, Syria, human rights activists said Monday. Al Jazeera reported 43 people died in the attack, though BBC News put the death toll higher at 53. Dozens others were injured.

It's unclear if Russian or Syrian planes carried out the strike, Britain-based Syrian Observatory for Human Rights said. The organization said at least five children and three police officers died.

Atareb is located in part of Aleppo province where Russia, Iran and Turkey designated a de-escalation zone earlier this year. Two weeks ago, the three countries announced plans to make these areas no-fly zones. Hostilities against the Islamic State and Hay'et Tahrir al-Sham militant groups are excluded from the agreement. Though there has been a drop in violence in these zones, clashes have occurred.

Syrian regime forces carried out heavy missiles shelling on the area of Jobar – Ayn Tarma, in the outskirts of al-Rahman Legion-held Eastern Ghouta, in the capital of Syria, Damascus, the Syrian Observatory for Human Rights reported on Sunday.

SOHR revealed that the Syrian regime forces fired missiles on the area of Jobar – Ayn Tarma, in the outskirts of the Eastern Ghouta, while added that the shelling was accompanied by heavy machineguns fire by the regime forces on the same areas. Meanwhile, clashes continued between the al-Rahman Legion militants and the regime forces and their allied militias in the area.

The Syrian Observatory for Human Rights reported, yesterday, that the regime forces also shelled the outskirts of the city of Ayn Tarma and other areas in Jobar neighborhood, east of the capital of Syria, Damascus, while carried out extensive assaults to secure their advance into the area.

The ongoing clashes are concentrated in al-Masher front and other areas, while other clashes took place in the vicinity of Jober neighborhood and Ayn Tarma Town; in the meantime, the regime forces conducted heavy shelling on the al-Rahman Legion-held areas, the SOHR added.

The Syrian Observatory for Human Rights documented that the Syrian regime forces launched more than 30 artillery shelling on Jobar neighborhood and its outskirts, in addition to Ayn Tarma, while also fired 12 missiles on several areas in the same neighborhood and carried another shelling on an area in Hamoriya Town and Haza Town, leaving 7 civilian casualties.

In the same context, At least 50 people, including 20 children, have been killed in Russian airstrikes and artillery attacks on eastern Syria since Friday, AFP said, citing the Syrian Observatory for Human Rights.

The shelling targeted areas along the Euphrates River in Deir Ezzor province, including two camps for the internally displaced, according to AFP. A number of airstrikes on Sunday targeted river crossings around the town of Boukamal, which was recaptured by ISIS from government forces on Saturday.

“Five civilians, including two children, were killed in the strikes on Al-Soussa crossing about 5km [3 miles] east of Albu Kamal,” the head of the SOHR told AFP, giving an alternative name for Boukamal. “Six civilians were killed in raids on another river crossing 20km [12.5 miles] north of the town,” he added.

In Boukamal, The so-called Islamic State recaptured its last stronghold in Syria on Saturday, only two days after the Syrian government declared victory over the militant group, Agence France-Presse reported.

Citing the U.K.-based Syrian Observatory for Human Rights (SOHR), AFP said that pro-government forces, including Iraqi militias and the Lebanese Hezbollah, retreated from the town of Boukamal, near the Iraqi border, after clashes with ISIS militants.