An F/A-18E and An F/A-18F (front) Super Hornet stand ready on the US navy's super carrier USS Dwight D. Eisenhower in the Mediterranean Sea on July 7, 2016. (Photo credit: ALBERTO PIZZOLI/AFP/Getty Images)
It is believed five individuals were on board a KC-130 and two individuals were in a F/A-18, two US defense officials told CNN. At least one Marine had been rescued just before 6 p.m. ET, according to a Marine Corps spokesman.
"Search and rescue operations continue for US Marine Corps aircraft that were involved in a mishap off of the coast of Japan around 2:00 am Dec. 6," local time, a statement by the US Marine Corps reads.
The planes "had launched from Marine Corps Air Station Iwakuni and were conducting regularly scheduled training when the mishap occurred," according to the statement.
The crashes happened approximately 200 miles off the coast of Iwakuni, Japan, a US Marine Corps official tells CNN.
The primary mission of a KC-130 is airborne refueling. It is not known at this time if the aircraft was refueling at the time of the crash.
"The circumstances of the mishap are currently under investigation," the statement said..
"Japanese search and rescue aircraft immediately responded to aid in recovery," according to the statement.
Wednesday's incident comes on the same day that the Marines released a report on a crash in July 2017, also involving a KC-130 variant that killed 15 Marines and one sailor.
That KC-130T crash took place in Leflore County, Mississippi, and the "investigation determined that the aircraft's propeller did not receive proper depot-level maintenance during its last overhaul ... in September 2011, which missed corrosion that may have contributed to the propeller blade" coming loose during the flight and going into the aircraft's fuselage, according to a Marine Corps statement on the investigation.