MARIETTA – (WAOK/AJC)  -  More than a dozen high school students were taken to a hospital today after their school bus collided with a car.  It happened Friday morning on North Marietta Parkway,  when investigators say a car attempting to turn left,  onto Polk street,  failed to yield,  and was t-boned by the bus.   A 12-year od in the car was seriously hurt and airlifted from the scene.  13 students on the bus and the bus driver were transported to Wellstar Kennestone Hospital for treatment of non life threatening injuries,   and later released.   All of the students were  headed to Marietta High School.    The young boy who was most seriously hurt,  was a student at nearby Marietta Middle School.