Authorities said a veteran pilot and a wing walker were killed instantly. The aerial daredevil walked the length of the aircraft while it flew in the air.
The crash happened at around 12:45 p.m. at the Vectren Air Show near Dayton.
Dangling from a single engine plane, wing walker Jane Wicker thrilled the crowd.
As the plane was about to the flip upside down, the announcer told spectators to watch pilot Charlie Schwenker.
"Keep an eye on Charlie," said the announcer. "Watch this! Jane Wicker sitting on top of the world."
But in the blink of an eye, the plane slammed into the ground and burst into flames. Wicker and Schwenker did not survive the impact.
On Wicker's Facebook page, fans and friends reacted to the following statement: "It is with sad hearts that we announce that Jane Wicker and Charlie Schwenker were tragically killed while performing at the Vectren Dayton Airshow. We ask for your prayers for the families and privacy of all involved and allow them time to grieve and work through these events."
Staff members from the FAA Flight Standards District Office witnessed the accident.
"They are communicating with the National Transportation Safety Board and they will continue their investigation but right now there's not any conclusive answers as to why the accident happened," said Dayton Aviation Director Terry Slaybough.
Wicker started wing walking in 1990. Wicker's website says she responded to a classified ad from the Flying Circus Airshow in Bealteton, Va., in 1990, for a wing walking position, thinking it would be fun.
She told WDTN-TV in an interview this week that her signature move as hanging underneath the plane's wing by her feet and sit on the bottom of the airplane while it's upside-down.
"I'm never nervous or scared because I know if I do everything as I usually do, everything's going to be just fine," she told the station.
This was her first time performing at the Vectron Air Show. The show was cancelled after the deadly crash Saturday, but was set to resume Sunday.
"It's important to make sure that everyone understands that the performers who do perform have a very strong bond and feel a strong need to continue the show," said Michael Emoff of the U.S. Air and Trade Show.
According to her website, Wicker said there was an enormous amount of practice and fine tuning that went into performing at air shows. She had never before had any close calls.
The Associated Press contributed to this report.