At least seven people were killed and 25 injured when a bomb exploded in a car in Syria's al-Raqqah province on Wednesday, the media reported.The blast targeted one of the Kurdish administrative institutions in the city of Tell Abyad, controlled by the US-backed Syria Democratic Forces (SDF), Xinhua news agency reported. The toll is likely to rise.The Islamic State militant group withdrew from the city in June 2015 after the Kurdish-led fighters launched attacks under the air cover of the US-led coalition.