All 16 troops aboard a Marine Corps air refuelling and transport aircraft were killed when the plane crashed in a field in rural Mississippi, officials confirmed today.
Authorities provided few details on what went wrong, or the nature of the Marines' mission.
The KC-130, an air refuelling aircraft that can also carry troops and cargo, took off from a Marine Corps air base at Cherry Point, North Carolina yesterday and disappeared from radar over Mississippi, crashing in the late afternoon.
"A Marine Corps KC-130 transport aircraft crashed in LeFlore County, Mississippi, on July 10 at approximately 4:00 pm CDT (2100 GMT), claiming the lives of 16 service members," the Marine Corps said in a statement.
The cause of the crash is under investigation.
US President Donald Trump, in a tweet, said the news was "heartbreaking."
"Melania and I send our deepest condolences to all!" he added.
Mississippi congressman Steven Palazzo said on Twitter he was "devastated," and offered prayers for the families of the victims.
The plane crashed in a soybean field in a largely rural area in the western part of the state.
All the victims were on the Marine Corps aircraft and there were no survivors, Leflore County emergency management director Fred Randle told CNN.
Helicopter footage taken by local news station Fox 40 showed a large gash in a green field, with fiercely burning fires sending up plumes of black smoke.
Firefighters sprayed the aircraft with huge layers of foam to quell the blaze.
Randle told NBC News that the scene was unsafe due to the presence of fuel.
The FBI was on hand, along with local and state emergency responders and investigators, he said.
Mississippi Governor Phil Bryant called for prayers for "those hurting after this tragedy."
"Our men and women in uniform risk themselves every day to secure our freedom," he said in a brief statement on Facebook.
The names of the victims were being withheld pending notification of their next of kin.
Accidents involving US military aircraft are not uncommon, but rarely do they claim so many lives.
The crash of a twin-engine C-23 Sherpa in the southern state of Georgia in March 2001 claimed the lives of 21 people.
In April 2000, 19 people were killed in the crash of a Marine Corps MV-22 Osprey, a tilt-rotor aircraft that flies like a plane but can hover and land like a helicopter.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)