One American serviceman has been killed and three injured in a US-led attack on an al Qaeda headquarters in Yemen.
It is the first US combat death under Donald Trump's administration. The special forces raid was authorised by the new President, a US military official said.
At least 14 al Qaeda fighters died in the assault, which US Central Command said also led to the discovery of
"Information that will likely provide insight into the planning of future terror plots".
Another US serviceman was injured in a "hard landing" at a nearby location.
Yemeni officials said a number of Saudis were among those killed and injured in the attack.
They added that senior local al Qaeda leaders - Abdul-Raouf al-Dhahab, Sultan al-Dhahab, and Seif al-Nims - were among the dead.
A third family member, Tarek al-Dhahab, was killed in a US drone strike several years ago.
An al Qaeda member described the attack as a "massacre", and claimed women and children had been killed.
He said the troops had been dropped in from Apache helicopters for the raid near Yakla village in Bayda province.
Tribal leaders said the US troops were hunting al Qaeda leader Qassim al-Rimi. They added the troops left with at least two unidentified individuals.
A US official, however, said no prisoners were taken.
Al Qaeda in the Arabian Peninsula has been seen to be behind a number of plots to target the mainland US.
It has exploited the civil war in Yemen to seize control of large areas of the south and east.
Yemen is among the seven Muslim-majority countries whose citizens have effectively been banned from entering the US for at least 90 days.