The Biden administration this week will reunite its first group of migrant families who were separated at the border under the Trump administration, Homeland Security Secretary Alejandro Mayorkas said Monday.

The announcement about the four families marks the first public update on the efforts of the administration’s task force, created via executive order in early February, dedicated to locating and reunifying migrant families separated by U.S. border officials during the former Trump administration’s “zero-tolerance” policy on unauthorized border crossings.

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“The Family Reunification Task Force has been working day and night, across the federal government and with counsel for the families and our foreign partners, to address the prior administration’s cruel separation of children from their parents,” Mayorkas, who chairs the task force, said in a statement.

He also indicated that parents deported without their kids may have the opportunity to return to the U.S.

“Today is just the beginning,” Mayorkas said, adding that more family reunifications will follow. The task force is due to provide a more complete update on its efforts by June 2.

The task force was created to fill one of President Joe Biden’s campaign promises to prioritize the reunification of migrant children who are still separated from their parents, nearly three years after the Trump administration formally launched and ended its separation policy.

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Michelle Brané, who previously served as the director of migrant rights at the Women’s Refugee Commission, was tapped to lead the unification effort full time.

The American Civil Liberties Union, which challenged the zero-tolerance policy in court, found that at least 5,400 migrant children had been taken from their parents at the border during the Trump administration, both during the policy’s formal implementation in 2018 and during predecessor pilot programs.

According to an April 7 status report, attorneys are still trying to reach the parents of 445 children, down from 506 kids as reported in February. The organization estimated that the parents of 302 of those children had been deported from the U.S. without them.

A steering committee established as part of the ACLU litigation is working “in parallel and in conjunction” with the Biden administration’s task force, according to court filings.

In reuniting some children with parents who have been deported, the Department of Homeland Security said it has established a process to accept requests for “parole,” or permission to reenter the U.S., from families outside the country.

The State Department has also sped up efforts to process requests for travel documents for separated families outside of the U.S., and the Department of Health and Human Services is working to provide additional services to support separated families, according to DHS.

Meanwhile, the task force is “exploring options for long-term legal stability for reunified families,” the department said, signaling that the Biden administration may still be open to granting legal status to migrant families separated under the prior administration’s policies.