Activists said at least 135 people were killed, while Syrian media said the death toll was at least 300, CNN reports.
The so-called Syrian Observatory for Human Rights, a Britain-based group close to Syria's foreign-backed opposition, said the dead included 50 Syrian forces or local fighters and 85 family members of security forces from the village of Bghailiye.
At least 42 ISIL fighters died, the London-based group said.
The death toll was much higher and was made up of civilians, Syria's news agency SANA reported.
SANA said ISIL militants killed about 300 residents of the village. Most of the victims were women, children and seniors, SANA reported, citing sources in Deir Ezzor province. SANA didn't report any deaths among the combatants.