Two United States Army helicopters returning from a training schedule in Alaska on Thursday crashed after colliding with each other, leaving three soldiers dead and a fourth injured.

According to John Pennell, a spokesperson for the U.S. Army Alaska, each of the AH-64 apache helicopters involved in the crash was carrying two people.

“This is an incredible loss for these soldiers’ families, their fellow soldiers, and for the division,” Maj. Gen. Brian Eifler, commanding general of the 11th Airborne Division, said in the Army statement. “Our hearts and prayers go out to their families, friends, and loved ones, and we are making the full resources of the Army available to support them.”

The army stated that the names of the victims of the crash are being withheld until their immediate families are notified.

The crash occurred near Healy, Alaska, while returning to Fort Wainwright, near Fairbanks.

The cause of the crash is under investigation.

In a statement from Joint Base Elmendorf-Richardson, Alaska, the helicopters were part of the 1st Attack Reconnaissance Battalion, 25th Aviation Regiment at Fort Wainwright.

First responders arrived on the scene of the crash but not much could be done to save the soldiers.

The incident was the second of such accidents involving military helicopters in the state.

In February, two soldiers were injured when a military helicopter — an Army AH-64D — was involved in a rollover accident in Talkeetna, Alaska.

The helicopter was also part of the 25th Attack Battalion at Fort Wainwright.

In March, nine soldiers were killed when two U.S. Army Black Hawk helicopters crashed during a routine nighttime training exercise.

The crash took place northeast of Fort Campbell, Kentucky and the helicopters involved were part of a medical evacuation unit.