A U.S. military aircraft crashed in rural Mississippi on Monday, leaving sixteen service members dead, according to the U.S. Marine Corps.

The KC-130T Hercules transport aircraft disappeared from air traffic control radar over Mississippi around 5 p.m. Monday, the Marine Corps said in a statement, after it departed from the Marine Corps Air Station Cherry Point in North Carolina.

“On behalf of the Marine Corps Reserve, I extend my deepest sympathies to the loved ones of those who perished in last night’s tragedy,” said Lt. Gen. Rex C. McMillian, Commander Marines Forces Reserve, in a statement. “The Marines and Sailor involved in this incident were among our finest.”

The aircraft crashed in a field in LeFlore County, Mississippi, about 100 miles north of the state’s capital, Jackson. The Marine Corps on Tuesday that all passengers onboard—15 Marines and one Navy Corpsman—were killed in the crash. Identities of the deceased are being withheld until next of kin were notified.

showed a plume of smoke billowing above the wrecked plane. The cause of the crash is unknown and remains under investigation.

Deployed in 1983, the KC-130 Hercules was designed by Lockheed Martin, and is used for air-to-air refueling, tactical passenger missions, and cargo transport, . The aircraft can carry either 92 ground troops, or 64 paratroopers and equipment, the Navy says, and it’s capable of being situated as a medical evaluation platform to hold attendants and 74 patients on stretchers.