The move signals the scope of a growing humanitarian and political crisis for the administration of President Joe Biden, a Democrat who took office on January 20.
The Biden administration said Friday it will end a Trump-era policy that let US border agents collect information about the immigration status of people who came forward to care for unaccompanied migrant children so it could potentially deport them.
The Health and Human Services (HHS) department is now holding about 8,800 migrant children and the US Customs and Border Protection has hundreds more in their charge, with more arriving every day.
Migrant children apprehended at the border are supposed to be transferred out of Border Patrol custody within 72 hours. But amid the coronavirus pandemic, the department has been strained trying to accommodate the influx since shelters had until recently been operating under limited capacity.
Fema will support a government-wide effort over the next three months to safely receive, shelter and transfer minor children who arrive alone at the United States southwest border, without a parent or other adult, Homeland Security Secretary Alejandro Mayorkas said on Saturday.
"I am grateful for the exceptional talent and responsiveness of the FEMA team", Mayorkas said in a statement.
The official said that HHS had expanded its capacity by 200 beds in the last week, but that opening new facilities would take time, including a 15-day notification period for Congress.
A Homeland Security official previously said the spike in children arriving at the border has drawn a lot of attention and meetings are ongoing "at the highest levels".
Unaccompanied minors found crossing the border are transferred by immigration officials to another federal agency, the Department of Health and Human Services (HHS).
She said the Biden administration inherited a broken system, and even went as far as to say migrants were fleeing Central America because of so-called "climate change".
Doocy asked Psaki what the Biden administration is doing to protect the citizens of border towns in Texas, where illegal immigrants are testing positive for COVID at a rate of nine percent, which, Doocey noted, is "more than double the national average".