The status of the crew members was not immediately known, the U.S. Army's Fort Campbell said in a statement to Reuters, without providing the number of people who were on board.
"We’ve got some tough news out of Fort Campbell, with early reports of a helicopter crash, and fatalities are expected," governor Andy Beshear said in a post on Twitter, adding that local authorities and emergency services were responding to the accident.
Crew members were flying two HH-60 Black Hawk helicopters, operated by the 101st Airborne Division, which crashed at around 10:00 p.m. ET (0200 GMT Thursday) in Kentucky's Trigg County, Fort Campbell's public affairs office said.
"The command is currently focused on caring for the service members and their families," the statement said, adding that the cause of the crash was under investigation.
The HH-60 is a variant of the Black Hawk helicopter designed to provide support for various military operations, including air assaults and medical evacuations, according to the US Army.