BROOKLYN - Police are investigating a hit-and-run accident that has left a woman dead on Flatlands Avenue last night.According to investigators, the 56-year-old victim was crossing the street at Flatlands and Utica avenues shortly after 10 p.m. when a car slammed into her and took off from the scene. The woman was taken to Brookdale Hospital, where she was pronounced dead. So far, police have no description of the vehicle or the driver. Anyone with information on the accident is being asked to call Crime Stoppers at 1-800-577-TIPS.