Six dead in Sydney seaplane tragedy

Six people have died in a seaplane crash in Sydney's north.

The bodies of all six people on board the plane have been recovered from the waters of Cowan Creek at Jerusalem Bay.

The plane crashed just after 5pm Sunday afternoon (local time).

"The sequence of events leading up to the accident are not yet understood, however following the impact with the water, the aircraft is reported to have sunk rapidly," an Australian Transport Safety Bureau spokesperson said.

"There are currently no reports of survivors."

Police have yet to release information on the identities of those on board, but unconfirmed reports say they are an 11-year-old boy, four Brits and the pilot.

One witness told the Nine Network he saw the plane hit the water.

"It made a tight right-hand turn and as it actually turned around, the wings dipped and it nosedived straight into the water."

The operator, Sydney Seaplanes, has suspended all planned flights as an investigation into the crash goes on.

"We wish to pass on our heartfelt condolences to the family and friends of the passengers and pilot who were tragically killed," managing director Aaron Shaw said.

"We do not yet know the cause of the accident."