Two US Army helicopters have crashed in Kentucky during a routine training mission, causing “several” casualties, military officials said.

The two HH-60 Black Hawk helicopters, part of the 101st Airborne Division, crashed at around 10pm on Wednesday in Trigg County, Kentucky, according to a statement from Fort Campbell.

The 101st Airborne confirmed the crash, saying on Twitter that it resulted in “several casualties” but did not specify whether those were injuries or deaths.

“Right now our focus is on the Soldiers and their families who were involved,” it added.

Kentucky governor Andy Beshear had said earlier that fatalities were expected, adding that police and emergency officials were responding.

The crash is under investigation.

“The crash occurred in a field, some wooded area,” Kentucky State Police Trooper Sarah Burgess said at a news briefing. “At this time, there are no reports of residence damage.”

Fort Campbell is near the Tennessee border, about 60 miles north west of Nashville, and the crash occurred in the community of Cadiz.

Nick Tomaszewski, who lives in Cadiz, told WSMV-TV that he sees helicopters from Fort Campbell pass overhead often, but the two that flew by on Wednesday stood out.

“I told my wife, ‘wow, those look really close tonight’ for whatever reason… about a minute later, they were coming across and there was a large explosion in the sky almost looked like a firework went off. And then the entire tree line lit up.”

Last month, two Tennessee National Guard pilots were killed when their Black Hawk helicopter crashed along an Alabama highway during a training exercise.