MELBOURNE - At least three people were confirmed dead after a light-plane crashed off the Victorian seaside town of Barwon Heads on Australia's south coast.

It was believed those who died in the four-seater plane, which pitched into the sea about 12.30 pm, were two men and a woman.

Earlier reports said five people had died in the crash. Victoria Police later confirmed the number was three, although there were reports that a further passenger was still missing.

Geelong local area commander Inspector Graham Banks said a witness observed the plane crash into the sea.

"Shortly thereafter he called police, water police attended and located what was a large area of wreckage and three deceased persons," he said.

"Currently police are in the process of searching for further wreckage and further other persons involved, although we don't believe there will be more than one or two person involved at most because we believe the plane was a four-seater plane."

Rescuers in boats and helicopters remain at the scene, with two air ambulances also dispatched to the area.

The township has a small airport but a spokesman for the airport told the Australian Associated Press that all planes from that airport had been accounted for and they didn't know where the crashed plane had flown from.