An independent witness called to report that a male punched a small child while aboard a bus which was parked in the bus zone. Officers responded and made contact with all parties. According to the witness, the child (7 years old) was arguing with her 4 year old sibling when the grandfather punched her in the face to end the argument. An ambulance was summoned to treat the 7 year old. The grandfather was taken into custody. Once cleared by medical staff (no visible injuries), the 7 year old and her sister were turned over to their mother (who responded to the scene). The grandfather was booked into the Glen Dyer Jail for the willful harm to a child charge.