Scared and hungry: Young boys cross the border alone

In pitch darkness, on a dirt road in the Rio Grande Valley of south Texas, is where local county deputies found 9-year-old Yossell and his 10-year-old friend Joseph, both traveling without their parents to cross the U.S. southern border.

Along the way, they joined entire families who also were heading to the U.S. to find refuge, including other unaccompanied minors like 15-year-old Jeffrey, who had been traveling by foot, train and bus for over two months.

He says he memorized the phone number of family he hopes to reunite with in Florida.

"Only God knows what will happen next," said Jeffrey, speaking in Spanish.

Yosell also walked most of the way, traveling for more than a month from his home in Honduras. His mother had given him a lifeline for him before he left: On the bottom of his pink hat, she had written her father's -- Yossell's grandfather's -- phone number.

When authorities first approached him, he pulled out the hat, and as if by reflex, pointed to the number.

The two young boys, strangers to one another, were scared and hungry. When ABC News Chief White House Correspondent Cecilia Vega approached them, they were about to be taken into Border Patrol custody.

Asked if he had family in the United States waiting for him, Yossell once again took the hat out of his bag, pointing to the phone number.

"My grandfather. His name is Marco," he told Vega.

Then, carefully, he returned the hat to his book bag.

Yossell's grandfather, Marco, lives in North Carolina, staying in touch with his mother who remained in Honduras. ABC News chose not to disclose their last names out of concern for their privacy and safety.

Marco said Yossell's mother sent him on his own because they had heard U.S. immigration authorities were turning families away, but not children.

She's not wrong.

The Biden administration has removed thousands of families under a public health order held over from the Trump presidency designed to alleviate capacity strains on Border Patrol. During the Trump administration the order also applied to unaccompanied kids, but the Biden administration has reversed that practice.

As a result, the numbers of unaccompanied kids in Border Patrol facilities have ballooned to record levels. More than 5,000 kids reside in USBP custody as they await transfer to the Department of Health and Human Services Office of Refugee Resettlement.

New images released by Customs and Border Protection Tuesday show tight quarters in a Donna, Texas, temporary processing facility. Children and teens can be seen packed into clear plastic pods inside the large, white tent structure.

The Biden administration has been scrambling to expand shelter space more appropriate for long-term care. The San Diego Convention Center is the latest site to be taken over by HHS.

"Every child in our care deserves a safe place to rest and to know their well-being is addressed," HHS Secretary Xavier Becerra said in a statement. "The County and City of San Diego has generously offered to partner with the Department as we abide by the law to provide unaccompanied children with food, sanitation and shelter."

San Diego government officials are projecting each minor will stay 30 to 35 days on average. The Federal Emergency Management Agency and the Centers for Disease Control are also involved in the effort to bring the convention center online as a shelter for migrant children.

This comes as another site for migrant minors is already reaching capacity. At the convention center in Dallas, eight more buses of kids arrived overnight Monday. Both FEMA and the CDC have been called in to assist local authorities in managing the arrivals.

The kids aren't the only ones worried about the consequences of their long journey. Immigration authorities and law enforcement officials along the border, now tasked with child care, are concerned how the strain on resources could affect public safety.

"It's kind of scary to me," said agent Jon Anfinsen, Vice President with the National Border Patrol Council. "When we're stuck inside processing, the border in certain areas is wide open."

Yossell is currently in Border Patrol custody.

His grandfather, Marco, says he has yet to receive a phone call from immigration authorities.

Editor's note: This story has been updated to correct the spelling of Yossell's name.