At least 10 Yemeni women and children have been killed in the first US military operation in the country authorised by President Donald Trump, medics and local media have said.
The US military said it killed 14 members of al-Qaeda in the Arabian Peninsula (AQAP)in Sunday's dawn raid in the southern province of al-Bayda that involved missiles and helicopter machine guns.
In a statement, the Pentagon did not refer to any civilian casualties, although a US military official, speaking on condition of anonymity, said they could not be ruled out.
The official also said that one US commando died, three others were wounded and that military forces did not take any prisoners from the site.
AQAP said Abdulraouf al-Zahab, a senior leader of the group, was killed along with several other fighters in the raid on the area that has been a frequent target of US drone strikes.
Medics in al-Bayda's rural Yakla district put the death toll at around 30, including 10 women and children.
The eight-year-old daughter of Anwar al-Awlaki, a US-born Yemeni preacher who was killed in a 2011 drone attack, was also among the victims, family members said.
Her grandfather Nasser al-Awlaki, a former minister of agriculture said: "she was hit with a bullet in her neck and suffered for two hours".
"Why kill children? This is the new [US] administration - it's very sad, a big crime," he told the Reuters news agency.
Fahd, a local resident who asked that only his first name be used, told Reuters that several bodies remained under debris and that houses and a local mosque were damaged.
Trump called the operation a success and said intelligence gathered during the operation would help the United States fight "terrorism".
"Americans are saddened this morning with news that a life of a heroic service member has been taken in our fight against the evil of radical Islamic terrorism," Trump said in a statement.
Stephen Zunes, the head of the Middle Eastern Studies Program at the University of San Francisco, said this kind of intervention has only provoked more backlash against the US in the past.
"Drone strikes and intervention over the past 15 years have stirred up more terror, extremisim and anti-Americanism than it has curbed, and this incident will once again resume the debate whether this is an effective counter-terrorism strategy," he told Al Jazeera.
The US has stepped up its use of drone strikes in recent years and is the only force known to be operating unmanned aircraft over Yemen.
AQAP and the Islamic State of Iraq and the Levant (ISIL, known as ISIS) have exploited Yemen's two-year war to carry out assassinations and bombings, mostly in lawless areas in the south.
According to the UN, more than 10,000 people have died - nearly half of them civilians - since a Saudi-led coalition launched air strikes on Yemen in March 2015.