The Beech Bonanza aircraft's occupants were believed to be a 56-year-old man and a 23-year-old woman, police said.
The plane plunged into the Stockleigh property, south of Brisbane, barely 10 minutes after taking off from Archerfield Airport on Monday morning.
"As to what happened whilst that aircraft was in the air, we have no information at this time," Chief Superintendent Mel Adams told reporters.
"It was a very confronting scene, as you can imagine."
Initial investigations indicated the plane took off at 10.57am, police said.
At about 11.10am, emergency services were called to the property following reports of a plane crash and grass fire.
Crews arrived and found plane debris scattered on the property and flames racing across an area about 300m by 400m, authorities said.
Multiple crews worked to quickly contain the blaze, which burned close to a farmhouse before being brought under control.
No homes were damaged.
Police held a press conference on Monday afternoon and initially did not comment on the plane's occupants, saying next of kin notification was still underway.
"As you can understand, this is a really sensitive matter, and we won't comment further on those persons that lost their lives today," Supt Adams said.
Police later confirmed a man and woman had died.
"Officers located two occupants of the aircraft, believed to be a 56-year-old man and a 23-year-old woman, both from Ascot, who were both declared deceased," the statement said.
A safety cordon remained in place at the site late on Monday, with police working closely with the Australian Transport Safety Bureau.
The bureau said it had begun an investigation with a three-strong team specialising in aircraft operations, maintenance and engineering sent to the site.
They were gathering evidence and examining the site and wreckage, recovering aircraft components for further examination at the bureau's technical facilities in Canberra.
"Investigators will also interview any witnesses and involved parties, and collect relevant recorded information including flight tracking data, as well as pilot and aircraft maintenance records, and weather information," the bureau said in a statement.
A preliminary report on the crash was set to be published in about eight weeks.
Anyone with vision of the crash or who saw the aircraft in the lead-up to the tragedy was being urged to contact police.
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