cairo suicide car bomb explode saturday syria eastern city deir al-zor kill injure dozens syrian state news agency sana report deir al-zor west bank euphrates river large important city eastern syria center country oil production syrian government friday declare victory islamic state deir al-zor big blow jihadists last stronghold syria crumble early saturday british-based syrian observatory human right say least one islamic state car bomb kill dozens people refugee gather east side euphrates river car bomb explosion kill injure dozens syria 's deir al-zor sana