California Highway Patrol investigators had no leads in the search for two men in a hit-and-run accident that critically injured a truck driver who had stopped to aid another on the Santa Ana Freeway in Irvine over the weekend. The CHP said William Sutton, 38, of Downey, suffered a fractured skull and two broken legs in the incident near the Laguna Canyon Road exit. Sutton had helped two passengers out of a truck that had jack-knifed, according to investigators. He was standing on the right shoulder of the freeway when a car traveling about 60 m.p.h. hit him. The CHP said the two men in the car fled on foot. A check of the car's license plate number did not turn up any suspects, officers said. Sutton, a driver for Mayflower Van Lines, was in critical condition at Western Medical Center in Santa Ana.