Krysta Gearhart was taken to the hospital after gun seller Geoffrey Hawk, the owner of In Case of Emergency, shot her in the thigh with a semi-automatic .380.
The demonstration is usually done with plastic models, but Hawk used a real gun with a round in the chamber.
"Everybody paused for a second and their initial reaction was making sure there wasn't more, and then they rushed to her aid," witness Eric Bower told WNEP. "I think the dealers were upset because it makes them look bad."
Hawk could be charged with reckless endangerment if the Columbia County district attorney signs off on the move. The misdemeanor charge can result in a maximum sentence of two years in prison and a $5,000 fine.
A sign at the show plainly stated that "loaded weapons are not allowed."