A lifeguard competition turned into a real-life rescue when a small plane crashed into the sea off southern California.

Corinne Baginski was at Huntington Beach to watch her 17-year-old daughter compete when she heard the aircraft hitting the water.

She said she turned to the tent where the teenagers were waiting for the next event at the 2022 California Surf Lifesaving Association Junior Lifeguard Championship, and saw them start to run towards the plane.

The young lifeguards were told to stay on the beach, while the professionals quickly paddled out to the single-engine Piper Cub that floated on its wings.

The plane went into the ocean about 27 metres from shore, according to the Coastguard.

Ms Baginski said the crash happened between events and no-one was in the water where it came down.

The pilot appeared to emerge from the plane on his own and was sitting on top of it when the lifeguards reached him, she said.

He was later seen sitting on the back of a lifeguard vehicle on the beach with a neck brace. He was taken to hospital with minor injuries.

Ms Baginski said a boy on the beach said the plane appeared to lose power and the propeller was not working. “He actually saw the plane coming down,” she added.

The Federal Aviation Administration is investigating the crash.

The plane floated to the water’s edge, where the surf washed it back and forth.