NORTH STONINGTON, Conn. (WTIC Radio) - Police are investigating fatal motorcycle crashes Sunday in North Stonington and Seymour.State police say Cynthia Oliveras, 48, of New Haven, was killed Sunday evening when the motorcycle she was a passenger on, slammed into a guardrail on Interstate 95 southbound in North Stonington. The crash occurred between exits 93 and 92 shortly before 7:30 p.m.The operator of the motorcycle, Cesar Negron, 46, of New Haven, sustained serious injuries, said police. Anyone who witnessed the crash is urged to contact State Police Troop E in Montville at 860-848-6500.Meanwhile, in Seymour, police say a man who was operating a motorcycle was killed Sunday afternoon when it collided with a car at Route 67 and North Street. Police say the motorcyclist was pronounced dead at a local hospital, following the crash, which occurred around 2:15 p.m.The woman who was driving the car was not injured but was taken to a local hospital for evaluation, said police.The crash closed the intersection for several hours as police investigated.Anyone with information on the crash is urged to contact Seymour police at 203-881-7600.