Islamic State militants have reportedly slaughtered up to 280 people in the Deir ez-Zor province for alleged cooperation with the Syrian troops.

Local residents told Sputnik news agency the killings carried out in al-Bagilya settlement which received Russian airlifted aid earlier.

A source close to the Syrian government side said the Islamic State fighters killed at least 250 people, including pro-government fighters and their families when they attacked the neighborhoods of Begayliya and Ayash in the city.

Islamic State militants reportedly have killed “whole families.”

Hours after the attack, the governor of Deir ez-Zor province, Mohammad Qaddur Ajnyyja, told Sputnik that Syrian army has successfully freed the settlement from Islamic State control.

“ISIL militants entered in the village of al-Bagilya… last night and perpetrated a massacre of whole families. For this reason the army headed to this region to save the population. There were clashes with ISIL militants, they suffered significant casualties, the rest succeeded to flee to the neighboring areas controlled by ISIL,” Ajnyyja said.

The Lebanon-based Al-Mayadeen TV said that 280 people were killed, including children and women adding that the dead bodies were thrown in the Euphrates River, while 400 survivors were taken hostage.

Syrian state media reports that all the people killed were civilians, but local monitoring groups said that dozens of government troops were killed as well, as RT reported.

The Syrian Observatory for Human Rights said the militants killed at least 85 civilians and 50 troops stating, though, that the exact number is still unknown.

Reuters citing a source close to the government reported at least 250 people were killed, while some of the victims were beheaded.