Civilians were "likely" killed in a US commando raid in Yemen over the weekend and children may have been among the dead, the US military's Central Command said.
The January 29 raid against Al-Qaeda in the Arabian Peninsula has garnered wide attention because a Navy SEAL was also killed and several more wounded in what marked the first operation of its kind authorized by President Donald Trump.
A Yemeni provincial official had previously said 16 civilians were killed in the raid -- eight women and eight children -- but CENTCOM did not provide any numbers.
"A team designated by the operational task force commander has concluded regrettably that civilian non-combatants were likely killed in the midst of a firefight during a raid in Yemen January 29. Casualties may include children," CENTCOM said in a statement.
The civilian deaths appear to have occurred when US aircraft were called to help the commandos as they conducted the dawn raid that US officials have said killed 14 AQAP members.
"The known possible civilian casualties appear to have been potentially caught up in aerial gunfire that was called in to assist US forces in contact against a determined enemy that included armed women firing from prepared fighting positions, and US special operations members receiving fire from all sides to include houses and other buildings," the statement read.
Officials were conducting an ongoing "credibility assessment" to see if there may have been additional civilian casualties in the intense firefight.
Navy SEAL Team Chief Special Warfare Operator William "Ryan" Owens, 36, was killed and three other US troops were wounded in the action.
Three more service members were injured when the tilt-rotor aircraft they were in made a hard landing.
That aircraft, a V-22 Osprey, was then intentionally destroyed by US troops to prevent it from falling into enemy hands.
CENTCOM described the raid as a "complex" situation that included small-arms fire, hand grenades and close air-support fire.
"Al-Qaeda in the Arabian Peninsula has a horrifying history of hiding women and children within militant operating areas and terrorist camps, and continuously shows a callous disregard for innocent lives," CENTCOM spokesman Colonel John Thomas said.
"That's what makes cases like these so especially tragic."
US special operations forces had mounted the raid in the Yakla region of Baida province against AQAP, which Washington views as the global terror network's most dangerous branch.
The raid snagged "an unbelievable amount of intelligence that will prevent the potential deaths or attacks on American soil," White House spokesman Sean Spicer said earlier.
But "you never want to call something a success 100 percent when someone's hurt or killed," he told reporters.
Trump and daughter Ivanka earlier flew from the White House aboard the Marine One presidential helicopter to Dover Air Force Base in Delaware for the repatriation of Owens' remains.