Suspected Islamic State group fighters killed at least 31 people foraging for truffles in Syria on Sunday, a monitor said, in the latest such attack in the war-ravaged country.The British-based Syrian Observatory for Human Rights also reported the killing of four shepherds by IS jihadists in a separate incident, and the abduction of two others."A total of 31 people, including 12 pro-regime fighters, were killed while collecting truffles in the desert east of (the central city) Hama," the Observatory said, giving a new toll.