US Department of Homeland Security Secretary Alejandro Mayorkas on Monday announced plans to reunite four migrant families separated at the US-Mexico border under the former Trump administration.

Mayorkas will oversee the reunifications under President Joe Biden’s newly-created Family Reunification Task Force — an Executive Order signed by President Biden in February.

“Our team is dedicated to finding every family and giving them an opportunity to reunite and heal,” Mayorkas told reporters. He continued:

They are children who were 3 years old at the time of separation. They are teenagers who have had to live without their parents during their most formative years. They are mothers who fled extremely dangerous situations in their home countries, who remained in dangerous environments in Mexico, holding out hope to reunite with their children.

Human rights advocates remain cautiously optimistic. “We are excited that these mothers will finally see their children after years, but the [American Civil Liberties Union] is certainly not prepared to celebrate just yet given the thousands who still need to be reunified and the more than 5,500 children who were traumatized and need help,” ACLU attorney Lee Gelernt said. “We are pressing for permanent legal status, compensation and social services. It is the least these families deserve given that our government deliberately abused them.”

President Biden created the Task Force on February 2 to help reunify families and provide them with necessary support structures, such as offering parents humanitarian parole to enter the US to find their children. The Task Force is currently working to create a database of all the families separated under Trump’s “zero tolerance” immigration policy, with some separations dating back to 2017.

The four families will be the first to be reunified under the Task Force directive, with more reunifications planned over the coming months. The Task Force will release its first report and progress update on June 2.