Emergency services are at the scene after the aircraft plummeted to the ground soon after departing Shellharbour Airport, south of Sydney, on Saturday morning.
Police said they were notified of the disaster about 10am.
The plane caught fire upon impact, with the flames extinguished by fire and rescue officers.
Three people are confirmed dead.
There are no reports of other people being injured.
Emergency services were on the scene within minutes but due to the fire, RFS personnel said it was unlikely anyone would have survived.
All first responders will be offered welfare support and counselling after attending the scene, Lake Illawarra Police District chief inspector Aaron Wunderlich said.
"It's quite a gruesome scene," he told reporters on Saturday.
"I'm guessing probably about 10 to 15 people ... may have witnessed it."
A crime scene has been established and the Australian Transport Safety Bureau has been notified.
Newly elected Labor MP for Kiama Katelin McInerney said the news from the airport was devastating.
"My thoughts are with the family and friends of those involved in the crash, as well as the dedicated first responders," she said.
In October 2024, three men died after two light air planes collided mid-air, one of which was on its way to the Shellharbour airport near Wollongong.
The crash sites, covered by bushland, were found near Belimbla Park in Oakdale in southwest Sydney.
The mid-air collision was believed to have occurred in uncontrolled airspace.
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