A spokesperson for U.S. forces in the region said they were still gathering information about the incident, Reuters reports.
A United States military V-22 Osprey aircraft with eight people onboard has crashed into the ocean in western Japan on Wednesday.
A spokesperson for the coast guard said it had no further details of the incident near Japan's Yakushima Island, including the status of those onboard.
A spokesperson for U.S. forces in the region said they were still gathering information about the incident, Reuters reports.
The crash happened about 2:47 p.m. local time (0547 GMT, with witnesses saying the aircraft's left engine appeared to be on fire as the aircraft descended toward the sea, Japanese broadcaster MBC reported.
“The cause of the crash is currently under investigation. Rescue efforts are underway, with further details expected,” a source said.
In August, a U.S. Osprey crashed off the coast of northern Australia while transporting troops during a routine military exercise, killing three U.S. Marines.
Another aircraft had crash-landed in the ocean off Japan's southern island of Okinawa in December 2016, prompting a temporary U.S. military grounding of the aircraft.
The tilt-rotor plane, which can fly both like a helicopter and fixed-wing aircraft, is operated by the U.S. Marines, U.S. Navy and the Japan Self Defense Forces.
The deployment of the Osprey in Japan has been controversial, with critics saying the hybrid aircraft is prone to accidents.
The U.S. military and Japan say it is safe.