Lanes of Twenty-fourth Street in Port Huron were closed yesterday as officials investigated a car-pedestrian accident at 24^th and Griswold.  A man and woman were believed to have been walking east across 24^th Street at the Griswold intersection when they were hit by a vehicle driven by a Port Huron man.  The victims who are reported to be in their late teens to early twenty’s were transported to area hospitals.  Authorities say the accident damaged the car’s windshield.  Port Huron Township Fire Department as well as units from the St. Clair County Sheriff’s Office and Port Huron Police Department worked the scene.