San Diego: The US military on Thursday confirmed the deaths of five Marines after a helicopter crash in southern California.
US authorities said a CH-53E Super Stallion helicopter went down on Tuesday night in Pine Valley, a hilly remote area east of San Diego.
The Marine Corps said efforts to recover the remains of the crash victims were underway and that an investigation had been launched.
The aircraft was flying from Creech Air Force Base in Nevada to Marine Corps Air Station Miramar near San Diego.
"It is with a heavy heart and profound sadness that I share the loss of five outstanding Marines from Third Marine Aircraft Wing and the 'Flying Tigers' while conducting a training flight," Major General Michael Borgschulte, commander of the Third Marine Aircraft Wing, said.
In a statement, US President Joe Biden said he was "heartbroken" at the loss of the service members.
"We extend our deepest condolences to their families, their squadron, and the US Marine Corps as we grieve the loss of five of our nation's finest warriors," Biden said.
"Today, as we mourn this profound loss, we honor their selfless service and ultimate sacrifice — and reaffirm the sacred obligation we bear to all those who wear the uniform and their families."
US military aircraft have been involved in a series of accidents over the past year, including the crash of a V-22 Osprey tilt-rotor aircraft off the coast of Japan in late November that killed eight service personnel.
Five service members died when a UH-60 helicopter crashed into the Mediterranean in a training exercise earlier the same month.
Another Osprey crashed and caught fire in Australia in August, killing three Marines. Three soldiers also died when two helicopters collided on the return from a training mission in a remote area of Alaska in April.