They said it happened at around 5am at the two mile marker on US Highway 27.
Officials reported that 24-year-old Lucas Gregory, of Whitley City, was driving along when his truck left the roadway.
They said this caused the truck to overturn, spilling thousands of gallons of gas over an embankment.
Both lanes of Highway 27 were closed for several hours as crews cleaned up the area.
Gregory was flown to UK Medical Center where his condition remains unknown.
Police do not believe he was under the influence of drugs or alcohol.