The incident occurred during military training in the US state of Kentucky.

The status of the crew members was not immediately known, Army spokeswoman Nondice Thurman said in a statement early on Thursday. It was unclear how many people were aboard the aircraft.

However, Kentucky governor Andy Beshear said deaths were expected and Kentucky police and the state’s emergency management service were responding to the accident.

“We’ve got some tough news out of Fort Campbell with early reports of a helicopter crash and fatalities are expected,” he said on Twitter.

We’ve got some tough news out of Fort Campbell, with early reports of a helicopter crash and fatalities are expected. @kystatepolice, @KentuckyEM and local officials are responding. We will share more information as available. Please pray for all those affected.

— Governor Andy Beshear (@GovAndyBeshear) March 30, 2023

Crew members were flying two Black Hawk helicopters that crashed at about 10pm (02:00 GMT Thursday) in Kentucky’s Trigg County, Thurman said.

The cause of the crash is under investigation. “The command is currently focused on caring for the service members and their families,” she said.