At least one car bomb struck the SDF-controlled city of Raqqa, with local Kurdish and Arab media outlets saying there were a number of casualties, including several dead.
Kurdish news portals said a mine exploded, followed by two car bombs that left several dead, including women and children. Other local Arab portals said at least four died in the explosion.
There has been an steady increase in attacks on areas controlled by the U.S. backed Syrian Democratic Forces that are mainly east of the Euphrates River.
The U.S.-backed group led by the Kurdish YPG militia has warned that Daesh (ISIS) militants would intensify an insurgency after their territorial defeat in their last enclave in Syria.