An elderly Westminster couple were in serious but stable condition after their car swerved off the San Diego Freeway and landed in a drainage ditch. Robert Rodda, 80, and his wife, Louise, 75, were traveling northbound near Harbor Boulevard on Sunday evening when their car drifted from the No. 2 lane to the freeway's right shoulder, California Highway Patrol spokesman Paul Caldwell said. The car, driven by Robert Rodda, traveled down an embankment and came to a stop in a ditch, about 100 feet from the freeway. The couple were taken by ambulance to the trauma center at Fountain Valley Regional Hospital. Caldwell said investigators are checking to determine whether Rodda may have suffered a heart attack at the time of the crash.