RICHMOND -- Wreckage from a plane that plunged into San Pablo Bay after colliding with another small plane Sunday turned up in the water Monday afternoon, and a Contra Costa Sheriff's Office spokesman said the search has turned into a recovery mission.

A Sheriff's Office infrastructure protection team found parts of the Cessna 210 about 2 p.m., Sheriff's Office spokesman Jimmy Lee said. Lee did not say immediately whether the search had turned up any signs of the pilot, who has been missing since the plane crashed about 4:05 p.m. Sunday.

A Federal Aviation Administration incident report said the lone occupant of the plane "is presumed fatally injured."

"What I can tell you is that this is no longer a search but rather a recovery mission," Lee said.

A 65-foot cutter and a Coast Guard helicopter scoured the water near the Point San Pablo Yacht Harbor for signs of the Cessna 210, Coast Guard spokeswoman Loumania Stewart said.

The Cessna collided with a single-engine Hawker Sea Fury TMK20 in midair, then plummeted into the water, authorities and witnesses said. The Hawker pilot landed safely at Eagle's Nest Airport in Ione, in Amador County, about 4:45 p.m. Investigators were still determining whether a second person was on that plane, Federal Aviation Administration regional spokesman Ian Gregor said in an email.

The plane was found in the bay about 13 feet below the surface, and approximately 1.5 miles from the Richmond shoreline, authorities said. A preliminary report on the FAA's website listed Sanders Aircraft, of Ione, as the owner of both planes. A man who answered the phone at Sanders Aircraft refused to comment Monday.

Officials said the two pilots appeared to be traveling together and had both left Half Moon Bay Airport, where they participated in a weekend air show.

According to witnesses, the two planes were close to each other at what seemed to be a low altitude when they appeared to collide, and the Cessna went plummeting into the water.

"I just happened to see them flying by close together. It didn't look like anything was wrong," Bonny Dunn said Monday. An aircraft mechanic, she said she was observing from a deck near the Point San Pablo Yacht Club. "All of a sudden, the Cessna started dropping and spiraling. At first, I thought the pilot might be showing off. But when the plane never pulled up, I just started shouting, 'It's crashing, it's crashing!'"

According to Dunn, who called 911 after witnessing the crash, the Hawker was in a right-banked turn when the planes collided. She said she wondered whether the pilot of the Hawker was aware of what happened, especially when that plane continued to fly away from the crash.

Witness Eric Johnson, who serves as a harbor master in the area, said the Cessna was missing a wing when it crashed. Witnesses said the plane went down approximately a mile north of Brother Island.

Gregor said the FAA and the National Transportation Safety Board were investigating the circumstances surrounding the crash.

Staff writer David DeBolt contributed to this report. Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.