Two soldiers were killed when their helicopter crashed during a training exercise at Fort Campbell in Kentucky, officials said Saturday.

The soldiers were members of the 101st Airborne Division. The crash happened Friday night and involved an Army AH-64E Apache helicopter.

The names of the deceased will not be released until 24 hours after next-of-kin notification is complete, officials said.

The crew was conducting routine training at the time of the accident. There were no other casualties. Fort Campbell Fire and Emergency Services members responded to the crash scene.

STRING OF US MILITARY AIRCRAFT CRASHES IN 2018 CONTINUES DEADLY TREND

“This is a day of sadness for Fort Campbell and the 101st Airborne,” said Brig. Gen. Todd Royar, acting senior commander of the 101st Airborne Division and Fort Campbell. “Our thoughts and prayers are with the Families during this difficult time.”

The cause of the accident was being investigated.

Three other U.S. military aircraft crashed this week, leaving five service members dead.

On Wednesday, an Air Force Thunderbird pilot was killed when his F-16 crashed near Nellis Air Force Base in Nevada.

On Tuesday, a Marin Corps CH053E Super Stallion helicopter crashed during a training flight in California, killing the four crew members on board.

MARINES IDENTIFY 4 KILLED IN HELICOPTER CRASH IN CALIFORNIA

Also Tuesday, a Marine Corps AV-8B Harrier crashed during a takeoff in Djibouti. The pilot survived after ejecting.

Fox News reported Friday that those crashes had lawmakers on Capitol Hill worried that the military's worn-out air fleet may not be getting the funding it needs.

At a press conference Thursday, the director of the Pentagon’s Joint Staff refused to say the crashes signaled a trend.

“I would reject ‘wave’ and ‘crisis,’” said Marine Lt. Gen. Kenneth F. McKenzie, Jr. “We’re are going to look at each one in turn. Each one is tragic. We regret each one. We will look at them carefully. I am certainly not prepared to say that it’s a ‘wave’ of mishaps or some form of ‘crisis.’”

Fox News Pentagon producer Lucas Tomlinson contributed to this report.