Tens of others were wounded, some critically, when unknown warplanes struck the town of Khusham in the eastern countryside of Deir al-Zour, said the Syrian Observatory for Human Rights.
It added that it wasn’t clear whether the strikes were carried out by Syrians or Russians.
The UK-based watchdog group said the attack on Khusham came just a day after 44 people, including 15 children and eight women, were killed in similar airstrikes against areas in eastern Deir al-Zour.
The Observatory said intense battles have been raging in Deir al-Zour since mid-January between Syrian government forces and the Islamic State (IS) group.
The battles are focused in the northwestern part of Deir al-Zour, where the IS group unleashed a wide-scale offensive on Jan.16 against Syrian army positions, managing to make some gains, according to the Observatory.
The watchdog group said days of battles were coupled with daily airstrikes by government forces. It added that over 200 government soldiers and 110 IS militants have been killed.
The Observatory, which relies on a network of activists on ground, said the IS group was making use of the tough weather conditions to make progress against the Syrian military positions.
It added that the terror group succeeded in capturing parts of the Ayash arm depots and the al-Saeka military camp during its offensive.
The progress has enabled the IS to open a supply line between its controlled areas in the western countryside of Deir al-Zour and the newly fallen areas in the northwestern part of the city.
Following its offensive in Deir al-Zour, the IS group stormed the town of Bughailiyeh, killing over 200 civilians and tossing their bodies in the Euphrates river, according to the Observatory.
It added that 400 civilians were snatched by the ultra-radical group in the town, 270 of whom, either minors or elderly, were later released as the rest will be interrogated on charges of dealing with the Syrian army.
The IS group has been suffering defeats recently in Syria during battles with Syrian ground troops who are backed by intense Russian air cover.
The group will feverishly strengthen its positions in Deir al-Zour, due to its strategic location near the Iraqi borders and its oil fields. The province is the richest among Syrian provinces in term of oil, one of the main lifelines of the IS group. Enditem