Killarney, Ont. - Police are looking into possible causes for a fatal crash involving a snowmobile Saturday evening.

Police say at approximately 5:40 p.m., a snowmobile, which was being driven across the ice surface of Georgian Bay at Covered Portage Cove, just northwest of Killarney, struck a protruding rock.

The crash ejected both female riders from the vehicle.

The driver of the snowmobile, 48-year-old Margaret Bateman, of Sudbury, Ontario, was transported to St. Joseph's Health Centre in Sudbury by air ambulance, where she succumbed to her injuries.

The passenger on the snowmobile, Loretta Tyson, also 48 years old, of Killarney, Ontario, was pronounced dead at the scene.