All six people on board a single-engine sea plane that crashed into Cowan Creek at Jerusalem Bay in Sydney's north on Sunday afternoon have died, police have confirmed.
The Sydney Seaplanes aircraft, carrying a pilot and five passengers, crashed about 3.15pm and a search and rescue operation was attempting to locate the aircraft which is believed to be submerged.
NSW Police confirmed three bodies had been recovered, and an operation was under way to recover the remaining three bodies. There was no further information on the identities of those on board.
There are unconfirmed reports that those on board were four British Nationals, an 11-year-old boy and the pilot.
The aircraft has not yet been recovered, and police said they were unsure whether it would be able to be recovered on Sunday evening.
The Australian Transport Safety Bureau identified the aircraft as a DHC-2 Beaver Seaplane which was "on a return flight to Rose Bay, Sydney Harbour" from Cottage Point Inn.
"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."
"There are currently no reports of survivors."
Commander of the Kurung-Gai Local Area Command, Acting Superintendent Michael Gorman confirmed all six on board had died.
"We are in the process of recovering the bodies of three other people ... (we will) see if we can recover the plane tonight or whether it will stay in situ tonight until tomorrow morning," acting Supt Gorman told reporters on the scene on Sunday.
"We don't know why the plane crashed."
Forensic police are on the way to Cowan Creek where they will try and identify the three bodies that have been recovered.
"(There) certainly were people out on boats and on the water which is why if people have seen what occurred please contact marine area command or crime stoppers," Supt Gorman said.
A spokesman for Sydney Seaplanes confirmed that an incident had occurred with a plane believed to belong to the company.
"We're just working with police to make sure that all assistance can be rendered," the spokesman said.
Seven News reported that phone footage taken by a group of men on a jet ski showed a Sydney Seaplane overhead, believed to have been captured "just moments before it is submerged".
The Australian Transport Safety Bureau will investigate the incident and release a preliminary report in approximately 30 days, with a final report expected to take up to 12 months.
The Westpac Life Saver Rescue Helicopter found an oil slick and several items of debris on the surface of Cowan Creek, spokesman Stephen Leahy said.
"There appeared to be a silhouette or outline of a small aircraft but it appeared to be submerged in deep water," he said.
"It was certainly too deep for us to access it and that's why the police divers have been called in."
Sydney Seaplanes offers scenic flights over Sydney tourist attractions and waterways including the Opera House, the Harbour Bridge and Pittwater, as well as the Hawkesbury River region.
The popular service has been operating for 80 years, and has carried high profile passengers such as Pippa Middleton and husband, James Matthews.
The Sydney Seaplanes spokesman said most of their scenic tours fly over the region in which the crash has occurred.
The aircraft crashed in Jerusalem Bay near Cowan which is located 30 kilometres north of the Sydney CBD.