A total of four fighters with the Kurdish-led Syrian Democratic Forces (SDF) were killed and six others wounded on Friday by a suicide bombing targeting the Kurdish forces in eastern Syria, a war monitor reported.The suicide bomber detonated his explosive-laden vehicle at a military post of the SDF in the town of Taianeh in the countryside of the eastern province of Deir al-Zour, said the Syrian Observatory for Human Rights.The UK-based watchdog group said that another explosion was heard on Friday evening when an explosive device went off while a vehicle of the SDF was passing by a school in the town of Shehel in Deir al-Zour.The Observatory said the Islamic State (IS) group is behind the bombings.The IS lost all positions in the eastern countryside of Deir al-Zour during a campaign led by the US-backed SDF late last year.Following its losses, the IS kept staging explosions in the areas controlled by the SDF.