PIERRE — A Pierre man and woman were arrested by Pierre Police Saturday night after an altercation on South Central Avenue. Pierre Police Captain Bryan Walz says officers were first called to the 300 block of South Central for a fight-in-progress call. Upon arrival on scene an officer saw the first suspect, identified as 54 year-old Darin Gravatt striking a defenseless person multiple times. As the officer attempted to break up the assault, the second person, identified by police as 51 year-old Julie Hamaker of Pierre, attempted to prevent the officer from intervening to break up the ongoing assault. Gravatt was eventually taken into custody on a single charge of aggravated assault. Hamaker was also arrested and charged with obstructing an officer and an outstanding warrant in another matter. The victim suffered serious injuries in the assault and was taken by ambulance to Avera St. Mary’s Hospital.