What we know about the immigrant children being detained separately from their parents

The debate over separating immigrant children from their parents is raging at the southern border and across the country, as images from the centers housing the kids have shown them, in some cases, inside structures made of chain-link fencing.

In other instances, buildings that used to house Walmart stores have been converted into facilities that look like large schools. But the children aren’t there by choice.

Here’s a roundup of the key information at the heart of the ongoing firestorm.

What is it like in the detention centers?

ABC News chief national affairs reporter Tom Llamas visited the Casa Padre detention center in Brownsville, Texas, with other reporters last week.

They were not allowed to film inside the facility, but the government contractor managing the facility shared video footage from their tour.

The Casa Padre facility was once a Walmart superstore but now houses nearly 1,500 boys between the ages of 10 and 17.

During the press tour, Llamas found the Casa Padre shelter to be clean, well-staffed, with several activities to keep the kids busy, also though the scheduled media visit had been announced.

The capacity is 1,497 people and on the night of Llamas' visit, 1,469 children were sleeping there, meaning the facility was at 98 percent capacity. They needed an extra bed in each room, so now there are five beds inside a 240-square-foot space, according to the government contractor.

The children are given three meals a day, along with two snacks. They have access to video games, pool tables, civics and English as a second language classes.

Only two hours are spent outside -- one hour in the morning and later in the afternoon -- and there are soccer fields and basketball courts for the kids to use.

That said, most of their day is spent inside the converted big-box store. Each child is assigned a clinician to help with any separation trauma or mental health issues.

There are no fenced-in structures at the Casa Padre detention center like those that have been reported at other facilities.

Who are the children inside the centers?

The detention facilities house unaccompanied minors who arrive at the border, as well as children who are separated from their parents by government officials at the border.

The system, which includes the separation of parents and children, stems from a "zero tolerance" policy U.S. Attorney General Jeff Sessions issued in early April.

That policy stipulates that the Department of Homeland Security (DHS) refer all cases of illegal entry to be criminally prosecuted.

As a result, the parents are detained and because the children are not charged with a crime, they are not detained with the parents.

How many children are being detained?

ABC News has been unable to determine the exact number of children being held by DHS, but The Associated Press last week obtained details on the number of children who have been separated from accompanying adults in the past two months as part of the administration’s policy.

There were 1,995 minors separated from adults in a six-week stretch this spring, from April 19 to May 31, the AP reported.

There were also other minors separated at ports of entry, with 64 such cases in March, 55 in April and 38 in May through June 6, according to the AP.

How the government views the centers

The minors “are very well taken care of,” Department of Homeland Security Secretary Kirstjen Nielsen said during a speech in New Orleans Monday morning.

“We operate in some of the highest standards in the country. We provide food, medical, education, all needs that the child requests,” she said.

The DHS oversees both U.S. Customs and Border Protection and U.S. Immigration and Customs Enforcement (ICE), which are the two agencies that handle adults who arrive at the border, whether illegally or legally by seeking asylum at a port of entry.

Where are the children held before the detention centers?

Before entering the detention centers, which the Department of Health and Human Services calls shelters, the children and adults go through processing centers.

ABC News national correspondent Marcus Moore Sunday went into the Rio Grande Valley Centralized Processing center in McAllen, Texas, which is run by Customs and Border Protection.

Inside, hundreds of men, women and children were divided among various holding cells. Some of the cells are made using gate-like materials, making them look like large cages.

In another part of the facility, a group of young children had gathered a central holding cell. The appeared to be resting on sleeping bags.

In other images from that facility, children are seen lying on mats with blankets that appeared to be made with tin foil, which could be similar to the foil wrap-type blankets used by runners after long races to retain body heat.

Who runs the detention facilities?

The facilities are run by private contractors hired by the Department of Health and Human Services.

HHS is the agency responsible for the care of unaccompanied children (both who arrive unaccompanied and those who are separated from their parents and therefore become unaccompanied).

The Casa Padre center in Brownsville is run by a private nonprofit called Southwest Key Programs. Ii also operates 26 other facilities, telling ABC News all its facilities are nearing capacity.

How many detention centers are there?

HHS told ABC News last week it operates a network of more than 100 shelters, which is the term they use for the detention centers like the one in Brownsville.

That was before another temporary shelter was created last week to meet growing demand.

Those shelters are located in about 17 states, a HHS spokesperson said.