(Gresham, OR)  --  An investigation is ongoing into a shooting that injured two young children in Gresham.  Police say a three-year-old and a five-year-old were playing in a yard off Northeast 165th Avenue last night when they were struck by bullets.  One of the children was hit in the foot, and the other was hit in the ankle.  Investigators believe the bullets came from a drive-by shooting.  Officers found 15 shell casings near the scene.