Japan's Defense Ministry says that two flight recorders have been recovered, along with other debris which they believe are from two Maritime Self-Defense Force helicopters that crashed.
Communication with the helicopters was lost late Saturday night when they were about 270 kilometers east of Torishima Island in the Pacific Ocean.
The ministry says that the recorders were found in the proximity of the area, and a mid-air collision may have occurred.
The SH-60K helicopters, each carrying four people, were engaged in nighttime training to search for submarines.
One person was rescued but later declared dead.
The ministry continues searching for the remaining seven people and will analyze the data from the recorders.
The Maritime Self-Defense Force has grounded all of its SH-60K aircraft.