RICHMOND — A massive search of the San Pablo Bay is underway for a pilot after two small planes collided, and one landed at an airport an hour away and the other dropped into the water, authorities said Sunday evening.

The collision between a single-engine Cessna 210 and a single-engine Hawker Sea Fury TMK 20 occurred about 4 p.m., authorities said. Each aircraft had only the pilot aboard, and the Hawker pilot was reportedly uninjured, authorities said. The condition of the Cessna pilot is unknown.

The pilot of the Sea Fury, a World War II British fighter aircraft, managed to fly about 45 minutes east and landed safely at the Eagles Nest Airport in Ione, in Amador County, said U.S. Coast Guard Petty Officer Third Class spokeswoman Loumania Stewart.

The Sea Fury is registered to Sanders Aeronautics in Ione, according to FAA records. A man who answered the phone there Sunday night declined to comment. It was not known late Sunday if the plane was damaged.

Federal Aviation Administration spokesman Ian Gregor said both planes took off from Half Moon Bay Airport.

The Hawker had been featured at the airport’s annual Pacific Coast Dream Machines Show featuring cars, show planes and custom motorcycles, said event spokesman Tim Beeman.

“It’s really a tragic way to end a really good day,” he said. “But we are still holding out hope.”

Beeman said the Hawker and the Cessna had participated in the show. The Cessna was being used as a chase plane, often used for real-time observations and taking air-to-air photographs of another aircraft in flight. Both were headed back to the Eagles Nest Airport in Ione.

The Cessna reportedly went down about a mile north of Brother Island.

Roslynn Johnson and her husband Eric Johnson serve as harbormasters for the area. Eric Johnson said someone from the marina took a boat to the crash area and found plane debris and an oil slick. He added that the Cessna lost a wing and was seen spiraling into the water.

Stewart said four Coast Guard boats and a Coast Guard helicopter searched for hours and into the darkness, but so far have only found debris.

Five police and fire boats from various agencies are also assisting, Stewart said. Private boaters also helped out at the start of the search.

Gregor said the Federal Aviation Administration and the National Transportation Safety Board are investigating the collision. Boaters should contact the Coast Guard if they find debris in the water, Stewart said.

Wire services contributed to this report. Reach Kristin J. Bender at kbender@bayareanewsgroup.com. Follow her at Twitter.com/kjbender.