The boy's heart-wrenching cries for his father. A young girl begging for someone to call her aunt. This, and more, can be heard on an audio reported to have been recorded in a border processing center where the Trump administration is separating children from parents and guardians.

Young children wail and cry out "Papá" and "Mami" in the audio, which was first reported by ProPublica from inside a U.S. Customs and Border Protection facility; a copy was provided to NBC News by civil rights attorney Jennifer Harbury. According to the attorney, the audio was recorded by a client who gave it to her. The client fears retaliation so is remaining anonymous. The recording has not been independently verified by NBC News.

It's clear in the audio the children are distressed. "Can I go with my aunt at least?" asks a young girl who tells officials she's memorized her aunt's number. "I want her to come." The other child continues to cry "Papá, papá." A woman in the audio says the girl hasn't eaten because she wants to first talk to her aunt.

"My mommy says they'll bring my aunt as soon as possible, so I can go with her," she said.

The children's cries elicit a response from a border agent: "Well, we have an orchestra here. What’s missing is a conductor.”

Outrage erupted over the weekend as more images of the administration's child separations emerged and were broadcast on television and shared in social media.

They showed children in cages made from chicken wire and sleeping on floors or mats covered only with mylar foil blankets for warmth. Images also showed the stark white tents that the administration erected in Tornillo, Texas, to hold the children.

The anger over the policy grew on Monday, with condemnation coming from all four living former first ladies.

Just two weeks ago, Sen. Jeff Merkley, D-Ore., was turned away when he tried to go inside a converted Walmart in Brownsville in far South Texas. But members of Congress have been going inside some facilities and bringing back stories from parents separated from children and children taken from their parents.

A limited group of reporters have been allowed in the Walmart that Merkley was prevented from entering, but cameras have been kept out.

Follow NBC News Latino on Facebook, Twitter and Instagram.