Two women were killed Thursday when a pair of light planes collided while flying over suburban Sydney, causing one of them to crash into the backyard of a home and burst into flames.

The two women, believed to be in their 20s, were pronounced dead at the scene after their single-engine plane crashed in Casula, New South Wales, police said in a statement. Nobody was in the house at the time of the crash.

In the other plane, the pilot, 25, and male instructor, 89, landed safely at a nearby airport, police said. Neither was injured and their single-engine plane sustained only minor damage. Officials were questioning the pair and have launched an investigation into the accident.

A covered patio attached to the house was demolished in the crash, police said. Two neighboring homes sustained minor damage from plane debris.

Witness Reg Dawes said the plane appeared totally out of control as it fell to the ground.

"I just seen this single little plane just spiraling right down," Dawes told Australia's Sky News television. "It made me feel real sick in the gut actually."