According to officials, Tony Grider, 41, and Simon Quinn, 22, were in the bucket portion of the ladder attached to the fire truck at the charity event.
As the event was winding down, the bucket was reportedly being moved when it encountered an electric energy threshold from a power line.
Police said it caused an "electric arc" that hit both firemen.
Investigators said two other firefighters, Steve Marrs, 37, and Alex Johnson, 28, then tried to lower the bucket to the ground, but were also shocked as electricity traveled down the ladder.
Officials said Grider and Quinn were both taken to an area hospital and then flown to the University of Louisville Hospital Burn Unit.
Officials said Grider is a 16-year veteran of the department.
Quinn works part-time for the department.
Marrs, who has served with the department for eleven years, and Johnson, who has served the department for three years, were treated at a local hospital, according to reports.
Police said Marrs has been released, while Johnson had been admitted for observation.
The incident remained under investigation.