WASHINGTON (AP) — Under the darkness of night, in the roiling high seas off the coast of Somalia, members of the U.S. Navy's SEAL Team 3 began to climb aboard an unflagged ship that was carrying illicit Iranian-made weapons to Yemen.

As Navy Special Warfare Operator 2nd Class Nathan Gage Ingram began climbing the ladder onto the boat, he slipped, falling into a gap the waves had created between the vessel and the SEALs' combatant craft. As he went under, Navy Special Warfare Operator 1st Class Christopher J. Chambers jumped into the gap to try to save him, according to U.S. officials familiar with the incident.

It was an instinctive act, honed by years of training, one teammate going to another's aid. But weighed down by their body armor, weapons and heavy equipment, the two SEALs plunged into the depths of the Arabian Sea and died, said the officials, who spoke on condition of anonymity to provide details of the Jan. 11 raid.

Chambers, 37, of Maryland, enlisted in the Navy in 2012, and graduated from SEAL training in 2014. His awards include the Navy/Marine Corps Achievement Medal with Combat “C” and three Navy/Marine Corps Achievement Medals. Ingram, 27, of Texas, enlisted in 2019, and graduated from SEAL training in 2021.

The mission came as the interdiction of weapons to Yemen takes on new urgency. The Yemen-based Houthis have been conducting a campaign of missile and drone attacks against commercial and Navy ships in the Red Sea and Gulf of Aden over Israel’s war on Hamas in the Gaza Strip. And U.S. retaliatory strikes have so far not deterred their assaults.

The 11-day search and rescue mission to locate the two SEALs was called off on Sunday and became a recovery effort. And on Monday, the Navy released their names, after their families were notified.

“Chris and Gage selflessly served their country with unwavering professionalism and exceptional capabilities,” said Capt. Blake Chaney, commander of Naval Special Warfare Group 1, which oversees SEAL Team 3. “This loss is devastating for NSW, our families, the special operations community, and across the nation.”

At the White House, President Joe Biden said in a statement that, “Jill and I are mourning the tragic deaths of two of America’s finest — Navy SEALs who were lost at sea while executing a mission off the coast of East Africa last week.” He said the SEALs represent “the very best of our country, pledging their lives to protect their fellow Americans. Our hearts go out to the family members, loved ones, friends, and shipmates who are grieving for these two brave Americans.”

The U.S. Navy's 5th Fleet is conducting an investigation into the incident. That probe is expected to examine whether the SEALs were properly equipped and trained for the mission, whether procedures were followed, and any decisions regarding the timing and approval of the raid, including the weather and the state of the seas.

According to officials, the commandos launched from the USS Lewis B. Puller, a mobile sea base, and they were backed up by drones and helicopters. They loaded onto small special operations combat craft driven by naval special warfare crew to get to the boat. It was the type of boarding for which SEALs train routinely, and illegal weapons moving from Iran to Yemen-based Houthis have been a persistent concern, particularly as the rebels continue to target commercial vessels in the region.

The team boarding the dhow was facing more than a dozen crew members. They ultimately seized an array of Iranian-made weaponry, including cruise and ballistic missile components such as propulsion and guidance devices and warheads, as well as air defense parts, Central Command said.

The raid was the latest seizure by the U.S. Navy and its allies of weapon shipments bound for the rebels, who have launched a series of attacks now threatening global trade in the Red Sea and Gulf of Aden. The seized missile components included types likely used in those attacks.

Chambers and Ingram, who were assigned to a West Coast-based SEAL unit, "were exceptional warriors, cherished teammates, and dear friends to many within the Naval Special Warfare community,” said Chaney.