Fighters from the Syrian Democratic Forces (SDF) are pictured together near the village of Baghouz, Deir Al Zor province, in Syria March 9, 2019.
The SDF said a week ago that it believed all civilians had come out and renewed its assault, leading to a new surge of displacement, including obdurate disciples of Islamic State, some of its captives and hundreds of surrendering fighters. In the last two weeks, many fighters appeared to be among those evacuating.
In Washington, a senior defense official estimated that almost 20,000 people, including 3,500 to 4,000 adult males, have emerged from Baghouz since February 20.
The report said most of the deaths were women and children.
The Kurdish-led SDF, with the backing of the USA -led coalition, has launched a crushing offensive to eliminate the IS from the eastern Euphrates River region in eastern Syria since September previous year.
"Most of those folks have moved elsewhere as part of our assessment of their movement toward a more clandestine insurgency or preparing for the next fight when they don't control territory", the official added.
The official said it would not be a surprise, based on current conditions, if it took another couple of weeks to finish mopping up the IS enclave.
Questions remain as to how aid planners, as well as SDF officials and their coalition partners, could have so severely underestimated the number of people left in the crumbling "caliphate".
"The message that these children are not wanted is growing stronger and stronger", said Geert Cappelaere, UNICEF's Middle East director.
The fighting began after a deadline expired for the group's armed men to surrender. But since Friday, only a small group has left.
Evacuated civilians have described awful conditions inside the village, with food scarce and people forced to hide underground to escape airstrikes and shelling by the SDF.
They said air strikes had targeted the militant group's weapons stores. Around a tenth of them are suspected of being jihadist fighters. The US-led coalition has been working for years to oust the group from cities and towns.
Evacuees are screened by the SDF as they emerge and are sent north to the al-Hol camp, already overcrowded with uprooted Syrians and Iraqis from years of war and struggling to cope with the influx.
The total population of the camp is now at 65,000 as aid workers are overwhelmed with shortage of tents and resources.
But their home countries have mostly been reluctant to take them back, with Britain stripping several women who have joined IS of their nationalities.
"You see how many people have come out in the past few days, there's that many still inside", said the mother of four, her bright green eyes peering through a black veil.
Russian Federation and Turkey brokered a cease-fire in September for Idlib, the last major stronghold of Syria's rebels.
The British interior ministry said it does not comment on individual cases.