(CNN) The United States continues to see a massive influx of migrants along the southern border, including many children. And while Border Patrol continues to detain a growing number of children, there are some fresh signs some of those children are being moved into more appropriate shelters designed to house them.
The number of unaccompanied migrant children in Border Patrol custody continues to climb, reaching more than 3,700 on Wednesday, many of them in jail-like facilities along the US-Mexico border, CNN has learned.
On Wednesday, US Border Patrol apprehended nearly 800 unaccompanied migrant children, as of the latest count, according to a Homeland Security official, signaling an ongoing spike in encounters of children and surpassing the current 450 daily average.
The spike in children arriving this week is drawing a lot of attention and meetings are ongoing "at the highest levels," the official said, predicting it will be an ongoing problem until the Biden administration finds a way to prevent children from arriving at the border.
"It's going to be very difficult to stop this," the official said.
After children are taken into Border Patrol custody, they're turned over to the Health and Human Services Department, which is charged with the care of migrant children. But amid the coronavirus pandemic, the department has been strained since shelters had until recently been operating under limited capacity.
In recent days, the number of children in HHS custody has also climbed indicating that the department is gradually absorbing the number of children crossing the US-Mexico border alone, taking them out of Border Patrol facilities and into shelters where they can be cared for.
There are around 8,800 unaccompanied for children in HHS custody, the department confirmed Thursday, up from last week when numbers hovered around 7,700.
But the administration still has to keep up with the accelerated pace of apprehensions on the border.
The administration is racing to house migrant children as President Joe Biden's approach to immigration faces a critical early test. The President entered office vowing to reverse what he cast as cruel policies put in place by President Donald Trump that made it difficult for people fleeing poverty and violence to come to the United States. Now, Biden is working to strike a balance between promoting a more humane approach to immigration while still sending the message to would-be migrants not to come.
At the peak of the 2019 border crisis -- when there were overcrowded facilities and children sleeping on the ground -- there were around 2,600 unaccompanied children in Border Patrol custody, a former CBP official previously told CNN.
As officials scramble to find shelter space for children, kids are staying in Border Patrol custody for prolonged periods of time, averaging more than four days.
More than 100 children have been in custody for around 10 days, CNN has learned. A week ago, the average time was 77 hours, above the 72-hour limit under US law.
Border facilities are "absolutely" overcrowded, the DHS official said. As of Wednesday, US Customs and Border Protection was overcapacity in 7 out of the 9 Border Patrol sectors, the official said, adding that Yuma, Rio Grande Valley and Del Rio were "severely overcapacity."
The Covid-19 pandemic has further constrained the space available to migrants in custody.
"I can't remember the last time I've seen the number that high," the official said about Wednesday's numbers, referring to a single day figure over the last several months.
On Wednesday, CBP announced it had encountered just over 100,000 migrants along the US-Mexico border in February, reaching levels not seen since 2019.
"(W)e continue to struggle with the number of individuals in our custody, especially given the pandemic," said Troy Miller, the senior official performing the duties of the CBP commissioner, during a press briefing Wednesday.
The border agency is working with HHS to move children out of custody as quickly as possible, said Miller.
"We need to move them out quicker," he acknowledged.
Facing an overwhelming flow of migrant children, HHS is now also assessing a NASA site for temporary housing.
"[O]n March 10, 2021, HHS, with the support of NASA, notified State and local officials that it will be conducting an assessment of NASA site Moffett Field located in Mountain View, California, for potential use as a temporary influx care facility for UC at some point in the future," Kenneth J. Wolfe, an HHS spokesperson said in a statement.
This story has been updated with new figures and additional context.