Three US soldiers were killed and another injured when two helicopters returning from a training mission in a remote area of Alaska collided mid-flight on Thursday, the US Army said.
Two soldiers were declared dead at the scene of the crash near Healy, Alaska, while a third died en route to the hospital, the 11th Airborne Division said in a statement.
A fourth soldier is being treated in the hospital for injuries sustained in the crash.
"This is an incredible loss for these soldiers' families, their fellow soldiers, and for the division," said Major General Brian Eifler, commanding general of the 11th Airborne Division.
The US Army did not identify the soldiers involved in the incident, and said names would be withheld until 24 hours after the next of kin are notified.
First responders arrived at the site, about 250 miles (400 kilometers) north of Anchorage, soon after the two AH-64 Apache helicopters from the Fort Wainwright base "collided in flight."
The incident is under investigation, according to the army, which did not say what caused the collision.
The helicopter crash is the second such incident in less than a month.
In late March, two US Army Blackhawk helicopters crashed during a training flight in Kentucky, killing all nine soldiers on board.
There have been multiple other crashes of US military aircraft in recent years, including another involving a Black Hawk that killed two Tennessee National Guardsmen during a training flight in Alabama in February.
Four US Marines were killed during NATO exercises in Norway last year when their V-22B Osprey aircraft went down, possibly after hitting a mountain, investigators said.
And two US Navy pilots were rescued after their T-45C Goshawk jet crashed during a training exercise in a residential neighborhood near Fort Worth, Texas in 2021. The pilots ejected before the plane went down.