The FAA and U.S. Coast Guard confirmed two planes collided midair and plunged into the ocean below at about 3:30 p.m. near Angels Gate Park.
Coast Guard officials stated during a news conference Friday evening that a debris field was found by a fisherman within five minutes of the planes going down.
Officials said debris was recovered, including a log book from one of the pilots, which indicated that two men, ages 61 and 81, were in one of the aircraft together.
A woman, 72, was the sole occupant of the other plane, according to the Coast Guard.
All the pilots involved were experienced flyers and had obtained a pilot license, officials stated.
Authorities said the two aircraft involved were believed to be a Beechcraft and Super Decathlon.
The Coast Guard said crews will search through the night and reassess the search Saturday morning.
Officials stated the water is warm enough for someone to survive overnight.
The Angels Gate Park entrance to the harbor was closed to help prevent interference with search efforts.