SAN DIEGO (AP) — The Coast Guard says investigators are trying to determine if there were any large ships in an area where a yacht was destroyed during a weekend race that killed three people off the California coast.Spokesman Lt. Bill Burwell says that investigators are also sifting Monday through debris of the 37-foot yacht, examining its GPS coordinates and reaching out to other race participants.Burwell says investigators aren't ruling out that the yacht hit rocks. Race organizers have said they believe the yacht collided with a larger vessel.Three crew members were found dead near Mexico's Coronado Islands. The fourth crew member is missing.