FORT CAMPBELL, Ky. — Nine people were killed in a crash involving two Army Black Hawk medical evacuation helicopters conducting a nighttime training exercise in Kentucky, Army officials said Thursday.

Nondice Thurman, a spokesperson for Fort Campbell, said the deaths happened Wednesday night in southwestern Kentucky during a routine training mission.

A statement from Fort Campbell said the two HH-60 Black Hawk helicopters, part of the 101st Airborne Division, crashed around 10 p.m. Wednesday in Trigg County, Kentucky. The 101st Airborne confirmed the crash about 30 miles northwest of Fort Campbell. The crash is under investigation.

The helicopters crashed in a field near a residential area with no injuries on the ground, Brig. Gen. John Lubas, the 101st Airborne deputy commander, said. One helicopter had five people aboard and the other had four, Lubas said.

An Army spokesperson declined to comment on whether the helicopters collided in the air.

“At this time, there is no determination on the specifics regarding the accident,” Daniel Matthews, a public affairs officer for the 101st Airborne Division, said in an emailed statement Thursday afternoon. Matthews said an aviation safety team from Fort Rucker, Alabama, will investigate the accident.

Speaking a news conference Thursday morning, Kentucky Gov. Andy Beshear said the state would do everything it can to support the families of those killed.

“We’re going to do what we always do. We’re going to wrap our arms around these families, and we’re going to be there with them, not just for the days, but the weeks and the months and the years to come,” Beshear said.

Lubas said it is unclear what caused the crash.

“This was a training progression, and specifically they were flying a multi-ship formation, two ships, under night vision goggles at night,” Lubas said. He said officials believe the accident occurred when “they were doing flying, not deliberate medical evacuation drills.”

The helicopters have something similar to the black boxes on passenger planes, which records the performance of aircrafts in flight and are used by investigators to analyze crashes.

“We’re hopeful that will provide quite a bit of information of what occurred,” Lubas said.

The Black Hawk helicopter is a critical workhorse for the U.S. Army and is used in security, transport, medical evacuations, search and rescue and other missions. The helicopters are known to many people from the 2001 movie “Black Hawk Down,” which is about a violent battle in Somalia eight years earlier.

Black Hawks were a frequent sight in the skies over Iraq and Afghanistan during the wars conducting combat missions and are also used by the Army’s 160th Special Operations Aviation Regiment. They were also often used to ferry visiting senior leaders to headquarters locations in the Iraq and Afghanistan war zones.

Fort Campbell is located near the Tennessee border, about 60 miles northwest of Nashville, and the crash occurred in the Trigg County, Kentucky, community of Cadiz.

Nick Tomaszewski, who lives about a mile from where the crash occurred, said he saw two helicopters flying over his house moments before the crash.

“For whatever reason last night my wife and I were sitting there looking out on the back deck and I said ‘Wow, those two helicopters look low and they look kind of close to one another tonight,'” he said.