The identities of the victims — four adults and two children — were not immediately known, Texas Department of Public Safety spokeswoman Tela Mange said.
The house is less than two miles from Lakeway Airpark, a privately owned airport created by residents of the Austin suburb.
There were conflicting reports on whether the twin-engine plane crashed while trying to land or had trouble gaining altitude after takeoff. Federal Aviation Administration spokesman John Clabes said the plane crashed as it made its second approach to land at the airport.
It was not immediately clear where the flight originated or was headed.
Five bodies were recovered from the wreckage. Crews worked hours after the noon crash to get the sixth from the burning home, Mange said. The impact of the crash left the plane in "very small pieces," she said.
"It was apparent when we got here there were no survivors," said Warren Hassinger, a spokesman with Austin-Travis County Emergency Management Services.
Three people inside the home — a retired couple, according to neighbors, and a third person whose relationship to the couple was not immediately known — escaped.
The back of the home, which overlooks the golf course, was blackened and charred, with rubble scattered all over the yard. The plane hit a 3- to 4-foot retaining wall, then plowed into the back patio and home. Smoke poured from a hole in the tiled roof for a few hours.
Todd Moore, who lives about 600 yards away, was golfing when the plane crashed. He said he ran to the house after seeing a plume of smoke to see if the retired couple who lived there was OK. He declined to name the couple.
Moore said neighbors told him the man who lived in the house saw the plane approaching as he stood on an upper patio, and he ran to his wife in the kitchen, grabbed her and ran out of the house. Apparently an appliance repairman also was in the home, witnesses said.
Ann Lowe, 19, who lives across the fairway, said she heard the plane over her house and then saw it disappear below the treeline. She ran outside, heard screams and then noticed her neighbor's house.
"I felt the heat and heard windows exploding in the house," she said.
Another witness, Michael Pickford, said he thought the pilot was having trouble gaining altitude.
"He was kind of holding the same altitude and you could hear the engine struggling, but he couldn't pick up at all," Pickford told News 8 Austin. "The back of the plane started to wobble a little bit and that's when he kind of started turning ... and probably about 45 seconds after he took off, that's when the engine cut off.
"He just did a huge nose dive, straight into the ground and ended up a little bit into the back of the house."
By Jim Vertuno
By Jim Vertuno