Throughout the nearly eight-minute recording, the tearful pleas of 10 Central American children who were separated from their family last week by immigration authorities can be heard. They yell “Mami” and “Papá” repeatedly without answer while a U.S. border patrol agent jokes about their crying.

“Well, we have an orchestra here, right,” the unnamed agent said in Spanish. “What’s missing is a conductor.”

Between April 19 and May 21, the U.S. government took roughly 2,000 children from their parents as part of the Trump administration’s “zero tolerance” policy on immigration, the Department of Homeland Security confirmed Friday. The leaked audio recording risks inflaming an already divided public over the separations and has fueled heated backlash from both political parties.

Last week, the American Psychological Association published an open letter warning President Trump of the “mental health crisis” caused by the separations.

“Research suggests that the longer that parents and children are separated, the greater the reported symptoms of anxiety and depression are for children,” it said.

At another point in the clip, a six-year-old Salvadorian girl pleads through tears for someone to telephone her aunt, according to ProPublica. She had memorized her number out of fear she might be forced from her parents.

“My mommy says that I’ll go with my aunt and that she’ll come to pick me up there as quickly as possible,” the girl said.

The aunt, who remained anonymous, spoke to ProPublica about the painful incident.

“I know she’s not an American citizen,” the aunt said of her niece. “But she’s a human being. She’s a child. How can they treat her this way?”

The children in the audio clip are between four and 10 years old and had stayed at the detention center for less than 24 hours at the time of the recording, according to ProPublica.