In what an official said was the first military raid carried out under President Donald Trump, two Americans were killed in Yemen on Sunday — one a member of SEAL Team 6 and the other the 8-year-old daughter of Anwar al-Awlaki, the New Mexico-born al Qaeda leader who himself was killed in a U.S. strike five years ago.

The raid in southern Yemen, conducted by the supersecret Joint Special Operations Command, was intended to capture valuable intelligence, specifically computer equipment, according to a senior U.S. military official. Three al Qaeda leaders were killed, according to U.S. officials.

Contrary to earlier reporting, the senior military official said, the raid was Trump's first clandestine strike — not a holdover mission approved by President Barack Obama. The mission involved "boots on the ground" at an al Qaeda camp near al Bayda in south central Yemen, the official said.

"Almost everything went wrong," the official said.

An MV-22 Osprey experienced a hard landing near the site, injuring several SEALs, one severely. The tilt-rotor aircraft had to be destroyed. A SEAL was killed during the firefight on the ground, as were some noncombatants, including females.

Nawar Anwar al-Awlaki, 8, was killed in an airstrike in Yemen ordered by President Donald Trump. Yemeni media / via Twitter

Defense Secretary James Mattis had to leave one of Washington's biggest annual social events, the Alfalfa Club Dinner, to deal with the repercussions, according to the official. He did not return.

On Monday, he released a statement identifying the dead SEAL as Chief Petty Officer William "Ryan" Owens and said, "Ryan gave his full measure for our nation, and in performing his duty, he upheld the noblest standard of military service."

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The senior military official said the 8-year-old girl, Nawar al-Awlaki, also known as Nora, was among the noncombatants killed in the raid, which also resulted in the death of several Yemeni women. U.S. officials said some of the women who were killed, however, were combatants and had opened fire on the SEALs as they approached the al Qaeda camp.

The girl's grandfather, Nasser al-Awlaki, Yemen's former agriculture minister, told NBC News a different story. He identified his granddaughter as the dead girl from a photo taken at the scene of the raid but based his description on what happened at the camp on conversations with what he characterized as Yemeni sources.

"My granddaughter was staying for a while with her mother, so when the attack came, they were sitting in the house, and a bullet struck her in her neck at 2:30 past midnight. Other children in the same house were killed," al-Awlaki said. He said the girl died two hours after being shot.

"They [the SEALs] entered another house and killed everybody in it, including all the women. They burned the house. There is an assumption there was a woman [in the house] from Saudi Arabia who was with al Qaeda. All we know is that she was a children's teacher."

Al-Awlaki said the girl and her mother had fled the Yemeni capital, Sa'ana, where he lives, to escape the heavy shelling.

The child's mother, Anwar al-Awlaki's widow, survived the raid with a minor wound, according to Nasser al-Awlaki. However, Anwar al-Awlaki's brother-in-law was killed in the raid. The death toll varies according to the sourcing, with the Pentagon saying 14 militants died, along with "numerous" civilians. Nasser al-Awlaki said Yemenis were circulating a body count of combatants and civilians as high as 59.

In explaining the attack, the senior U.S. military official told NBC News: "Al Qaeda is probably stronger in Yemen than in any other country. The U.S. has mounted in intense effort for the past three years from ship, air and drone to go after a reconstituting core al Qaeda organization in Yemen."

The raid, said the official, was directed from a U.S. base in Djibouti, across the Gulf of Aden from the southern tip of the Arabian peninsula and the western edge of Yemen. Officially, the United States was searching for "information that will likely provide insight into the planning of future terror plots."

Karen Greenberg, director of Fordham University's Center on National Security, said the girl's death will be a boon to al Qaeda propagandists.

"The perception will be that it's not enough to kill al-Awlaki — that the U.S. had to kill the entire family," she said.

Nawar's father, Anwar al-Awlaki was killed by a drone on Sept. 30, 2011, not far from Sunday's raid. The U.S. Justice Department had approved killing him in a memorandum that was disclosed in 2014. The memo concluded, "We do not believe that al-Awlaki's U.S. citizenship imposes constitutional limitations that would preclude the contemplated lethal action" by the U.S. military or the CIA.

Al-Awlaki, who was born while his father was a graduate student in the United States, moved to Yemen and became a prodigious propagandist who, the United States said in the memo, had played "operational and leadership roles" with al Qaeda and "continues to plot attacks intended to kill Americans."

U.S. intelligence also believed al-Awlaki was a potential successor to Osama Bin Laden, who had been killed six months earlier.

Nawar al-Awlaki is the second of Anwar al-Awlaki's children to be killed by U.S. forces. Two weeks after Anwar was killed in late 2011, his 16-year-old son, Abdulrahman, was also struck in a drone strike. U.S. officials said the younger al-Awlaki was in the wrong place at the wrong time — that he was with their intended target, an al Qaeda leader.

Intentional or not, Greenberg said, the deaths of three al-Awlaki family members will enhance the al Qaeda narrative. She noted that as part of propaganda efforts, terrorist groups have begun to circulate photographs of children reputedly killed by U.S. forces. Photos of Nawar al-Awlaki alive and dead are already circulating widely in Arab media.

Al Qaeda in the Arabian Peninsula released a statement via online jihadi media referring to the raid as a "massacre," said U.S. troops had fired on women and children "in cold blood," and accused the SEALs of having "no human values."

Rima Abdelkader contributed to this report.