Two people have died in a gyrocopter crash offshore from Western Australia's South West region.
A Civil Aviation Safety Authority spokesman told AAP the small recreational aircraft was flying along the shoreline at Forrest Beach, near Capel, at 2.19pm on Wednesday when it crashed.
Police and St John Ambulance were immediately called and rushed to the scene, but paramedics were stood down.
The Australian Sports Rotorcraft Association has been notified and will likely assist police with their investigation.
Police will prepare a report for the coroner.
An ASRA spokesman said the association's Queensland-based incident manager was flying to Perth to accompany his local counterpart and would arrive on Thursday morning.
CASA will look into the accident, but may not need to conduct a full investigation if the police probe is conclusive.
The Australian Transport Safety Bureau does not usually investigate sports accidents and a spokesman said authorities had not notified the government agency of the accident.
A gyrocopter aircraft is also known as an autogyro or a gyroplane.
They can only seat two people and are often homemade from kits.
The rotorcraft derives lift from freely turning rotor blades and the rushing air then spins the rotor as the aircraft is thrust forward by an engine-driven propeller, ASRA says.
Police said the exact make and model of the aircraft was not yet confirmed.
There had been unconfirmed reports it was a military helicopter, but a Defence spokeswoman referred inquiries to police.
There was a string of gyrocopter accidents in NSW late last year.
Two men aged in their 60s were killed crashing into a paddock near Orange in October.
Less than three weeks later, a 50-year-old man died after his gyrocopter crashed into farm machinery at a property near Moree.
In December, an elderly man suffered multiple injuries when he made a hard, forced landing in a field in Aberdeen.
