Two patrol boats conducted search patterns throughout the night and continued through 9:15 a.m., according to the U.S. Coast Guard.
The rescue operation transitioned to a recovery operation with the Los Angeles Sheriff's Department, according to a press release issued by the U.S. Coast Guard.
Diving and sonar operations were taken over by county officials to locate the wreckage and survivors.
Officials from the Coast Guard and the FAA said the two planes went down at about 3:30 p.m. Friday near the Angeles Gate Lighthouse.
Two men, ages 61 and 81, were in one of the aircraft together. A 72-year-old woman was the sole occupant of the other plane, according to the Coast Guard.
All pilots were experienced flyers with pilot licenses, the U.S. Coast Guard said.
The Angels Gate Park entrance to the harbor remained closed until further notice to help prevent interference with search efforts.
All traffic through Angels Gate were asked to re-route to the Queens Gate entrance.
The cause of the crash was still under investigation.