Two soldiers from the 101st Airborne Division’s 101st Combat Aviation Brigade were killed late Friday when their AH-64E Apache helicopter crashed at the local training area on Fort Campbell, Kentucky.

The incident happened about 9:50 p.m. Friday, the 101st Airborne announced Saturday morning. The crash is under investigation.

The names of the two soldiers will not be released until their families are notified.

The crew was conducting routine training at the time of the accident, according to the 101st Airborne. There were no other casualties.

Fort Campbell Fire and Emergency Services are on site and recovery operations are ongoing, officials said.

“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, in a statement. “Our thoughts and prayers are with the families during this difficult time.”

Friday’s crash comes on the heels of a difficult few weeks for military aviation.

On March 14, two Navy aviators were killed when their F/A-18F Super Hornet crashed during a training flight in Florida. A day later, seven airmen were killed when their HH-60 Pave Hawk crashed in western Iraq during a routine transit flight.

On April 3, two more crashes occurred. A Marine Corps AV-8B Harrier crashed during takeoff in Djibouti; the pilot ejected and survived. Later that day, a Marine Corps CH-53E Super Stallion helicopter crashed during a training flight in California, killing the four crew members on board.

And on April 4, an F-16 from the Air Force’s Thunderbirds crashed near Nellis Air Force Base, Nevada, killing the pilot.