A spokesman for III MEF, Capt. Eric Flanagan, said the mishap took place around 4 p.m. local time Saturday, or about 2 a.m. East Coast time. There were 26 personnel aboard the Osprey; 23 so far have been rescued, and a search-and-rescue effort continues for three Marines who have not been located.
The aircraft was assigned to Marine Medium Tiltrotor Squadron 265 (reinforced), out of Marine Corps Air Station Futenma, Japan. In April, VMM-265 became the aviation combat element of the 31st Marine Expeditionary Unit, which is continuously deployed in the Pacific.
"The aircraft involved in the mishap had launched from the USS Bonhomme Richard (LHD 6) and was conducting regularly scheduled operations when the aircraft entered the water," Flanagan said in a statement.
"The ship's small boats and aircraft immediately responded in the search and rescue efforts. The 31st MEU is currently operating with the Bonhomme Richard Expeditionary Strike Group as part of a regularly-scheduled deployment in the Indo-Asia-Pacific region," he said.
The mishap is under investigation, Flanagan said, and search operations are ongoing.
The Marine Corps also participates in rotational unit training deployments to Australia, known as Marine Rotational Force-Darwin, or MRF-D. However, in a message posted to the unit's Facebook account Saturday, MRF-D officials said no troops assigned to the rotation were involved in the V-22 incident.
For the Marine Corps, this is the second major aviation mishap of the summer. In July, a KC-130T transport aircraft crashed in Mississippi, resulting in the deaths of the plane's nine crew members and seven troops assigned to Marine Corps Forces Special Operations Command.
The last time a Marine Corps V-22 Osprey experienced a mishap was in December 2016, when a V-22 attempted a precautionary emergency landing off the coast of Okinawa, but crash-landed in shallow water instead. Members of the five-person crew were injured, but all survived the mishap.