U.S. officials on Tuesday were investigating the cause of a military transport plane crash that killed 16 service members including elite special operations forces a day earlier, leaving a miles-long trail of wreckage in rural northern Mississippi.

According to Reuters, the KC-130 Hercules aircraft disappeared from air traffic control radar over Mississippi after taking off from Cherry Point, North Carolina. It plunged into a soybean field at about 4 p.m. CDT (5 p.m. EST) on Monday in Mississippi’s LeFlore County, about 100 miles (160 km) north of Jackson, the state capital.

Fifteen Marines and one Navy sailor were killed, the U.S. Marine Corps said. The names of the deceased were being withheld until family members were notified. Further details were not released. Gen. Robert Neller, Commandant of the Marine Corps, pledged “a thorough investigation into the cause of this tragedy.”

Seven of the 16 who perished, including the sailor, were based at Camp Lejeune in North Carolina and were members of the elite Special Operations Command of the Marine Corps.

Seven of the 16 who perished, including the sailor, were based at Camp Lejeune in North Carolina and were members of the elite Special Operations Command of the Marine Corps.