UPDATE: At least 16 dead after military plane crashes in Mississippi

LEFLORE COUNTY, Miss. — A US Marine Corps transport plane crashed in rural western Mississippi on Monday afternoon, killing all 16 service members (fifteen Marines and one sailor) who were on board, officials said.

The KC-130, an aircraft that the Marines can use to refuel planes in the air as well as carry cargo, crashed in Leflore County at about 4 p.m., the service said.

Federal Aviation Administration officials contacted the Marines when the aircraft disappeared from air traffic control radar over Mississippi, officials said.

The cause of the crash wasn't immediately known, the Marines said. The plane went down just off US 82, about 85 miles north of Jackson, with debris found on both sides of the highway, CNN affiliate WDBD reported.

The flight originated from Marine Corps Air Station Cherry Point in eastern North Carolina, the Marines said. The service hasn't commented on the crew's mission, the itinerary or the destination.

CNN affiliates WDBD and WHBQ, citing officials they didn't name, reported the plane had stopped in Memphis, Tennessee.

The service members' names weren't immediately released.

"While the details of the incident are being investigated, our focus remains on providing the necessary resources and support to the family and friends of these service members as they go through this extremely difficult time," the Marines said in a news release.

Flames and dark smoke rose from part of the wreckage in a field off the highway, video from WDBD showed.

President Donald Trump called the crash "heartbreaking" on Twitter.

"Melania and I send our deepest condolences to all!" the President tweeted.

Correction: An earlier version of this story incorrectly reported the FBI is at the scene of the crash. The FBI told CNN on Tuesday that it is not at the scene.

Investigators are still working to determine the cause of the crash.

A release from the Marine Corps states: "The identities of the service members whose lives were lost in this tragic accident are being withheld to allow time for their loved ones to be notified. While the details of the incident are being investigated, our focus remains on providing the necessary resources and support to the family and friends of these service members as they go through this extremely difficult time.  More information will be released as it becomes available."