Emergency personnel stand along U.S. Highway 82 after a military transport plane crashed into a field near Itta Bena, Miss., on the western edge of Leflore County, Monday, July 10, 2017. Several were killed in the crash. (AP Photo/Andy Lo)
Emergency personnel stand along U.S. Highway 82 after a military transport plane crashed into a field near Itta Bena, Miss., on the western edge of Leflore County, Monday, July 10, 2017. Several were killed in the crash. (AP Photo/Andy Lo) Credit: Andy Lo

Itta Bena, Miss. — Investigators picked through debris across a fire-blackened soybean field on Tuesday to try to determine why a U.S. military plane slammed into the ground, killing all 16 people aboard in the deadliest Marine crash anywhere in the world in more than a decade.

The KC-130 air tanker was carrying members of an elite Marine special operations unit cross-country for training in Arizona when it went down Monday afternoon in the Mississippi Delta, the military said. The fiery crash scattered wreckage for miles around and sent a pillar of black smoke rising over the countryside.

Witnesses said they heard low, rumbling explosions when the plane was still high in the sky, saw the aircraft spiraling toward the flat, green landscape and spotted an apparently empty parachute floating toward the earth.

Fifteen Marines and a Navy sailor were killed. Their identities were not immediately released.

Bodies were found more than a mile from the plane.

It was the deadliest Marine Corps air disaster since 2005, when a transport helicopter went down during a sandstorm in Iraq, killing 30 Marines and a sailor.

The Marine Corps said the cause was under investigation and offered no information on whether the plane issued a distress call.

Marine Maj. Andrew Aranda told reporters that no foul play was suspected.