GREENWOOD, Miss. — A Marine Corps transport plane that crashed in Mississippi, killing 16 service members, experienced an emergency at high altitude and left two debris fields a mile apart, a Marine general said on Wednesday, bolstering witness accounts that the plane broke up or exploded while in the air.

“Two large impact areas are half a mile north of Highway 82 and a half a mile south of Highway 82,” said Brig. Gen. Bradley S. James, commander of the Fourth Marine Aircraft Wing, Marine Forces Reserve.

“Indications are something went wrong at cruise altitude,” he said. “There is a large debris pattern.”

The KC-130T, en route from Marine Corps Air Station Cherry Point in North Carolina to Naval Air Facility El Centro in California, crashed on Monday into a soybean field between the towns of Itta Bena and Moorhead, in the Mississippi Delta. It was ferrying members of the elite Marine Raiders special operations force and their equipment. After stopping in El Centro, the plane was to take them to Yuma, Ariz., General James said at a news conference a few miles from the crash site.

General James did not specify what he meant by “cruise altitude.” As a propeller-driven craft, the KC-130 family of aircraft does not fly as high as jet planes of similar size. It can go above 30,000 feet with a relatively light load, but it generally cruises below that level.

Appearing with General James, Marshall L. Fisher, commissioner of the State Department of Public Safety, warned that the wreckage contained explosives. He cautioned people in the rural area not to touch any debris, both for safety’s sake, and because removal of it could be a crime.

“There are items that are going to be recovered by teams on the ground; some of them may be unsafe,” he said. He later noted that “there are ordnance disposal teams in the area” who may be causing controlled explosions throughout the search.

The KC-130 family, consisting of four-engine turboprops, is a variant of C-130 transport, a venerable mainstay of the United States military. The KC-130T is designed for aerial refueling of other aircraft but can also be used to carry people and gear.

The aircraft that crashed bore registration number 165000 and was nicknamed Triple Nuts for the three zeros. It belonged to Marine Aerial Refueler Transport Squadron 452, or VMGR-452, nicknamed the Yankees, a Reserve unit based at Stewart Air National Guard Base in Newburgh, N.Y., about 60 miles north of New York City.

The plane was built in 1993. In its life, it refueled fighter jets patrolling the no-fly zone in Iraq before the 2003 invasion, and later it ferried troops and equipment into and out of the war zones in Iraq and Afghanistan, assignments that meant using rutted runways in dusty locales, according to records and photographs taken of it over the years.

Alan Stinar, a former marine mechanic who worked on this and other KC-130s, and is a historian of the model, said it also took part in at least two missions in Africa.

“These things are workhorses that can do almost any job the Marines need them to do, and during the war they were very, very busy,” Mr. Stinar said.

According to federal aviation records, the plane was damaged in 2004, when a wind storm tipped it sideways onto one wing, while it was on the ground in Fort Worth. In 2010, a storm piled so much snow on the plane that it tipped forward, its tail in the air, Mr. Stinar said.

Six of the people killed were members of the Second Marine Raider Battalion, based at Camp Lejeune in North Carolina, and one was a Navy medical corpsman assigned to that battalion. The other nine belonged to the Reserve squadron at Stewart Base.

The KC-130T was built between 1983 and 1995, and it is being phased out in favor of the newer KC-130J. The squadron at Stewart is the only Marine unit still using the KC-130T. Experts say that with proper maintenance, the planes’ age should not be a safety issue.