This cactus forest on the US-Mexico border was quiet one recent day. No mass crossings of migrant families. No sprinters. Just two men caught sneaking into the Arizona desert.
Then US Border Patrol Agent Daniel Hernandez spotted a youth alone under a juniper tree, dressed as if he were headed to church. When the agent approached, the teen quickly surrendered.
"Are you afraid?" Hernandez asked in Spanish. The youth nodded and said that his name was Marco and that he was from Guatemala. He was 14 but looked small in an oversize jacket, pressed shirt and pants, and too-large black Oxford shoes.
Hernandez lifted his sunglasses to appear less intimidating. He asked Marco who had left him, how he knew where the border was, and whether he carried food and water.
"Are you hungry?" he asked. "When was the last time you ate? Yesterday? You want a cookie?"
The deaths of two Guatemalan children in December and the massive groups of Central American families crossing the border are increasingly transforming the Border Patrol's role from national security to humanitarian relief, even as President Donald Trump declares the situation a national emergency.
Well-over half the people taken into custody in recent months have been parents and children, with hundreds surrendering at a time, often in isolated locations. In other cases, youths such as Marco are dropped off by themselves. More than 1,800 Central American parents and children, a record high, crossed illegally last week on the day Trump went to El Paso, Texas, to tout the need for a border wall.
Homeland Security Secretary Kirstjen Nielsen promised "extraordinary protective measures" after the deaths of Jakelin Caal, 7, and Felipe Gomez Alonzo, 8, who crossed into the United States separately with their fathers. Since then, the federal government says it has dramatically increased its medical staff at the border.
A Mexican man died in US Customs and Border Protection custody this week, however. And advocacy groups warn that the remote areas where families are crossing, and the agency's crowded detention facilities, still pose serious risks - especially for young children.
Medical teams from the Coast Guard, the Department of Health and Human Services, and new private contractors have been triaging and examining migrant children on the border. Border agents, hundreds of whom are also paramedics, are patrolling more far-flung areas, backed up by helicopters, buses and SUVs. The US military has also helped with the evaluation and treatment of migrants.
"We've been adapting to these new realities," said a senior adviser for Customs and Border Protection who was allowed to speak only on the condition of anonymity.
The deaths of Jakelin and Felipe remain under investigation, and the official said the Department of Homeland Security so far hasn't found any sign of a widespread public health crisis on the border. The biggest challenge, Border Patrol agents say, are the large groups of migrants - 200 to 300 people at a time - crossing in distant locations, swamping the agency's resources.
Fifty-eight large groups crossed from October to January, compared with 13 groups over the same period last year.
Some migrants arrive with colds, sprained ankles, broken bones, chickenpox and "gripe," otherwise known as the flu. A toddler who fell from a moving vehicle in Mexico was brought to the US border in January with a possible broken arm. A teenage girl cracked several vertebrae after slipping from an 18-foot-high border wall in December.
The CBP has given Border Patrol agents "enhanced" field guidance to check every child - including those arriving in large groups - and to ask if they are sick, injured, dehydrated or hungry. Agents have also stocked up on baby formula, diapers and women's sanitary supplies in sectors such as Yuma, where 90 percent of border crossers in January were family members and unaccompanied minors.
Migrants who are ill are sent to a hospital. The rest are taken to Border Patrol stations for more-comprehensive screenings. Doctors and nurses check their vital signs, take their medical histories and administer medicine.
In one instance, on January 24, the DHS flew in a physician and other staffers via helicopter to a Border Patrol station in the Tucson sector to examine 130 minors. Two youths with high fevers were taken to a hospital.
Still, the huge numbers of families arriving carry significant risk, officials say, because many cross into the United States in less-populated areas, with few agents and limited or no medical facilities.
The CBP official said the agency is deploying general-practitioner physicians who can treat a wide array of people - including children and pregnant women. But the American Academy of Pediatrics said it has urged CBP Commissioner Kevin McAleenan to hire medics trained in pediatrics, or at least accept volunteer pediatricians, because children require more specialized care.
"Sick children are very different from adults," said Colleen Kraft, the immediate past president of the academy, whose term ended December 31. "If you don't have the pediatric training... you're going to miss those children who are becoming very, very ill."
Doctors and advocates said young children should not be housed in cold and crowded processing cells, where migrants describe sleeping on mats on the floor under silver Mylar blankets.
"It's a law enforcement mentality," said Marsha Griffin, a pediatrician who volunteers at a shelter in McAllen, Texas, and the co-chairwoman of the academy's special-interest group on immigrant health. "They are treating people as prisoners, not as children and families."
On a tour of the Border Patrol's Tucson sector in January, agents did not allow a Washington Post reporter to visit the cells where migrants are held, citing privacy concerns. But some migrants recently released from those cells and dropped off in vanloads at a Tucson shelter praised the medical attention their children received in federal custody.
Julio, a schoolteacher from Guatemala, said his daughter Jakeline, 15, was taken to the hospital with the flu and had recovered.
"The care was excellent," he said, speaking at Casa Alitas, a Catholic Community Services of Southern Arizona shelter located on a palm-tree-lined street. Shelter officials asked that the migrants be identified only by their first names to protect their privacy.
The men said they and their children had spent up to three days in federal custody, with minimal food. They had not showered and had arrived at the shelter carrying their children's shoelaces and other belongings in plastic evidence bags.
Their faces lit up at the sight of a cozy living room of overstuffed couches, a television playing the movie "Coco," and bowls of apples and oranges. A cabinet contained Pepto-Bismol and other medication.
The White House has decried the influx of families across the border as a national security crisis and accused migrants of bringing their children with them and filing false asylum claims as a ploy to gain entry to the United States. Trump has said that "only a wall" can deter them from continuing to cross.
But advocates say migrants are determined to flee poverty, hunger and violence in Central America and have the legal right to seek asylum here.
"They're coming to the greatest country in the world," Teresa Cavendish, director of operations for Catholic Community Services of Southern Arizona, said of the migrants. "And we want to build a wall that keeps them out of it?"
Cavendish said her organization and other nonprofits are able to provide shelter and hot meals to the roughly 100 migrants a day being released in Tucson to await immigration court hearings. Last month, a local developer loaned a former monastery to use as a shelter through May. Most of those released from CBP custody leave the shelters within days to join relatives in Colorado, Nebraska, Arkansas and other states.
In interviews, the fathers staying at Casa Alitas acknowledged that they had brought their children because it meant they would probably be released. A federal court settlement limits how long the US. government can detain children with their parents.
But they also said they had picked the safest possible journey across the border.
"I don't want to lose my son," Demetrio, 30, said as Danny, 7, rode around the shelter's backyard on a bicycle.
Border Patrol agents say they take special care with children. But the large crowds of surrendering families rattle them, they say, because criminals sometimes hide in the mix. Agents say they are frustrated that parents are using children to gain entry into the United States, and they fault smugglers for taking them on risky journeys.
Agents were horrified to find a 6-year-old boy abandoned in the Arizona desert last year, in 100-degree heat. He carried a lunchbox and said he was looking for his mother in the United States. Children as young as toddlers have been heaved over high border fences to the desert sand below.
"I don't know any agent worth their salt that hasn't . . . gone home at the end of the day, sat down on the couch, didn't turn on the lights, didn't turn on the TV, but just sat there and thought about the day," Border Patrol Agent Jacob Stukenberg said during the tour of the Tucson sector.
He was with Hernandez when they spotted Marco, the 14-year-old from Guatemala, standing on the roadside as if he were waiting for a bus.
Hernandez could see the youth was healthy.
His eyes fell to Marco's new cellphone, which kept buzzing. Thirty-one missed calls.
"Who's calling you?" Hernandez asked.
"A man from my village," Marco said.
The smuggler, Hernandez thought.
Someone had ferried Marco from Guatemala to a Mexican highway that is steps from Organ Pipe Cactus National Monument, a 517-square-mile preserve of cactus, rattlesnakes and slumbering tarantulas.
Marco said it took a few days, traveling by bus and car. He had apparently stepped onto US soil through a rusty fence made from old railroad track. He wanted to go to Kentucky, to start a new life with a brother who lives there.
Hernandez listened until a Border Patrol transport vehicle pulled up.
Then he escorted Marco to the truck, made sure his seat belt was buckled and wished him good luck.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.