The desperate sobbing of 10 Central American children, separated from their parents one day last week by immigration authorities at the border, makes for excruciating listening. Many of them sound like they’re crying so hard, they can barely breathe. They scream “Mami” and “Papá” over and over again, as if those are the only words they know.

The baritone voice of a Border Patrol agent booms above the crying. “Well, we have an orchestra here,” he jokes. “What’s missing is a conductor.”

Then a distraught but determined 6-year-old Salvadoran girl pleads repeatedly for someone to call her aunt. Just one call, she begs anyone who will listen. She says she’s memorized the phone number and at one point rattles it off to a consular representative. “My mommy says that I’ll go with my aunt,” she whimpers, “and that she’ll come to pick me up there as quickly as possible.”

More than 2,300 of them have been separated from their parents since April, when the Trump administration launched its “zero tolerance” immigration policy, which calls for prosecuting all people who attempt to illegally enter the country and taking away the children they brought with them. More than 100 of those children are under the age of 4. The children are initially held in warehouses, tents or big box stores that have been converted into Border Patrol detention facilities.