Washington (CNN) Congressional Democrats are demanding answers on family separations at the US border and how parents will be reunited with their children.

In a letter Friday to the inspector generals for the Departments of Homeland Security and Health and Human Services, a group of Democratic lawmakers write that they are "deeply concerned" about the the Department of Justice's "zero-tolerance" policy that has resulted in family separations and "gravely disturbed" over reports about separated parents and children and the possibility that they might "never be reunited again."

The letter, organized by California Rep. Lou Correa and signed by more than 120 House Democrats, outlines a series of questions such as, "How quickly (average time) can DHS and/or HHS locate a child's parent?" and "What is the process for DHS and HHS to reunite parents with their children?"

President Donald Trump's decided earlier this week to reverse course and sign an executive order that he said would help keep families together. That decision came after intense backlash, including from congressional Republicans, against the administration's separation of undocumented immigrant parents from their children at the border.

But many questions over what happens next remain.

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