Flagstaff Police are investigating a fatal accident on South Lake Mary Road Sunday. Officials received a report of a collision involving a pedestrian and a vehicle at around 12:57 p.m. in the area of South Lake Mary Road and East Frontier Avenue. The driver of the vehicle remained on the scene and was placed under arrest for suspicion of DUI. The pedestrian was pronounced dead at the scene. The identities of both the driver and pedestrian are not known. The investigation into the incident is ongoing.