Two U.S. Navy SEALs lost in nighttime seas during a raid on a small boat off Somalia were declared dead Sunday.

The 10-day mission has shifted from search and rescue to recovery, U.S. Central Command said in a statement.

“We regret to announce that after a 10-day exhaustive search, our two missing U.S. Navy SEALs have not been located and their status has been changed to deceased,” it said.

The two were not publicly identified, and CENTCOM said no further information would be made immediately available “out of respect” for their families.

Two U.S. defense officials said one of the SEALs had tried to board the vessel amid rough seas and fell into the water. The second dived in after the first, as is protocol, the officials said.

The vessel, known as a dhow, was carrying “Iranian advanced conventional weapons” as the raid took place Jan. 11, CENTCOM said Sunday.

“We mourn the loss of our two Naval Special Warfare warriors, and we will forever honor their sacrifice and example,” Gen. Michael Erik Kurilla said in CENTCOM’s statement. “Our prayers are with the SEALs’ families, friends, the U.S. Navy, and the entire Special Operations community during this time.”

Somalia’s coastline includes the Gulf of Aden, the Guardafui Channel and the Indian Ocean. U.S. military officials, who did not give the exact location of the incident, said personnel from the U.S., Japan and Spain searched more than 21,000 miles of surface.

Assistance included help from the Fleet Numerical Meteorology and Oceanography Center, the U.S. Coast Guard Atlantic Area Command, the University of California, San Diego’s Scripps Institution of Oceanography and the Office of Naval Research’s Oceanographic Support wing.