The plane, piloted by Gerald H. Clayton of Columbus, crashed shortly after takeoff and plowed into the back of a house in a subdivision just south of Columbus Municipal Airport, said Columbus police Lt. Matt Myers.
Clayton and passenger Dennis King, 60, of Columbus, had already exited the aircraft when he arrived and spoke to one of the men, Myers said. They had burns, cuts and abrasions.
"He knew he was fortunate to be alive.
Neighbors said both men were able to walk to ambulances unaided after the crash in Columbus, a city about 40 miles south of Indianapolis.
Wishard Memorial Hospital spokesman Todd Harper said Clayton was listed in serious condition and King was in fair condition Thursday afternoon in the hospital's burn unit.
Hiroko Nakao, 51, said she was inside her home doing laundry when the impact of the crash shook her house, destroying a sun room and shattering windows. She fled to a neighbor's house uninjured and called her husband at work.
"She said, 'House is burning! Fire!" said her husband, Tadashi Nakao, 53. "I couldn't believe it when I got the phone call from her.
The crash occurred around 9:30 a.m. in a well-manicured neighborhood about a mile from the city's airport, Indiana State Police Sgt. Noel Houze said. Witnesses said they saw the plane flying extremely low and that its engine didn't sound normal just before the crash, which was followed moments later by a fiery explosion.
"He was losing altitude and I thought, 'He's going to crash,'" said Joe Andrew, who was washing his Corvette in his driveway when he noticed the plane.
Neighbor Marion Clavin told WTHR-TV that he heard two booms and went outside to investigate. He said he saw one person who had climbed out of the plane.
"He was bleeding and he was on fire. I told him, 'Roll on the grass, roll on the grass!'" Clavin said.
The man told him the pilot had already escaped the wreckage, Clavin said.
Retiree Larry Ruble, 63, lives across the street from the crash scene and said he knows the pilot, who he said he built the plane.
"He's a great guy. He built it himself and it's been up in the air a lot," Ruble said.
The Glastar GS-1 kit plane is registered to Clayton, according to Federal Aviation Administration records. A message left at Clayton's home was not immediately returned Thursday.
FAA records list Clayton as a private pilot since 2004 and as a repairman and builder of experimental aircraft.
FAA spokesman Tony Molinaro said the aircraft was destroyed in the crash. He said the agency's investigation will take anywhere from a few weeks to more than a month to complete.
The Nakaos, who moved to the United States from Japan four years ago, said they planned to stay in a hotel or with friends Thursday.
Hiroko Nakao said she feels fortunate she escaped injury.
"It was my worst experience ever," she said.