TOKYO, Japan — The U.S. Marine Corps has declared five Marines missing after an aviation mishap dead.

The five were on a KC-130 Hercules refueling aircraft that collided last Thursday with an F/A-18 Hornet during regular training. The warplanes crashed into the sea south of Japan’s Shikoku island.

Two Marines were rescued from the F/A-18, but one of those rescued died.

The search, joined by Japanese and Australian forces, was halted Tuesday, and the cause of the crash is still under investigation, the Marines said in a statement.

The identities of the Marines will be released after the next of kin are notified.

Japanese Prime Minister Shinzo Abe sent a message of condolences to U.S. President Donald Trump, while praying for a speedy recovery of the injured. Abe thanked American troops for their dedication and vowed to cooperate with Trump to further strengthen their alliance to promote regional peace and stability.

The Associated Press contributed to this story.