Dec. 7 (UPI) -- Authorities have expanded the search for five U.S. Marines who are still unaccounted for after two planes collided in mid-air off the coast of Japan.
Japan's ministry of defense said Thursday it's expanded the search area to account for ocean currents.
The incident, which killed at least one and hospitalized another, happened about 200 miles off the coast in the middle of an aerial refueling. The planes involved were a KC-130 that was attempted to refuel an F/A 18 fighter jet.
"The United States Marine Corps confirms that two Marines have been found. One is in fair condition and the other has been declared deceased by competent medical personnel," the branch said in a statement on Twitter.
A crew member in the fighter was taken to Marine Corps Air Station Iwakuni and another one from an unspecified plane was taken to a ship of the Japanese Maritime Self-Defense Force. Japan sent 10 aircraft and the Japanese coast guard dispatched six patrol ships as part of the rescue operation, government officials said.
The incident remained under investigation, but refueling at night while common during training can be more difficult for issues of depth perception. The KC-130 tanker aircraft is capable is refueling jets and helicopters mid-flight using what is called a "hose and drogue" system, where each aircraft must fly at the same speed and distance.
The two planes belonged to the U.S. Navy's 7th Fleet.
"The U.S. 7th Fleet is supporting ongoing search and rescue efforts with a Navy P-8A Maritime Patrol and Reconnaissance Aircraft flying out of Kadena Air Force Base, along with assistance from the Japan Maritime Self-Defense Force and the Japanese Coast Guard," a Navy statement said Thursday on Facebook.
The 7th Fleet is the Navy's largest fleet and covers more than 77 million square kilometers, from the International Date Line to the India-Pakistan border, down to Antarctica.