According to battle field sources, Syrian vanguard units entered headquarters of the Brigade 137 in west of the Deir ez-Zor city on Sunday night.
The Takfiri terrorist group of Daesh also started shooting mortars in the area to avoid the advance of the Syrian forces.
Deir ez-Zor is situated in eastern Syria, bordering Iraq.
The oil-rich city has been under the control of Daesh since July 14, 2014 and the humanitarian aids were only air dropped.