– In their final minutes together, Jean Carlos, 8, held his mother’s hand like an anchor and promised to “take deep breaths” so he wouldn’t cry. His sister, Crisol, 10, hid angrily in the kitchen. His brother, Cristian, 12, hauled a blue suitcase into the yard.

Past the family gate, Aura Fernández, 38, a single mother of 10, beat back a surge of tears. Her bus came rolling down the road. Then she kissed her children, climbed aboard and disappeared.

“I love you,” she said just before setting out. “Study hard.”

Seven years into an economic collapse, Venezuela’s migrant crisis has grown into one of the largest in the world. Millions have already left. By the end of 2020, an estimated 6.5 million people will have fled, according to the United Nations refugee agency — a number rarely, if ever, seen outside of war.

But hidden inside that data is a startling phenomenon. Venezuela’s mothers and fathers, determined to find work, food and medicine, are leaving hundreds of thousands of children in the care of grandparents, aunts, uncles and even siblings who have barely passed puberty themselves.

Many parents do not want to put their children through the grueling and sometimes very dangerous upheaval of displacement. Others simply cannot afford to take them along.

The exodus is so large that it is reshaping the very concept of childhood in Venezuela, sending grade schoolers into the streets to work — and leaving many exposed to the swirl of abusive players who have filled the vacuum left by the collapsing Venezuelan state, including sex traffickers and armed groups.

By one assessment, conducted by Caracas-based aid organization CECODAP and polling firm Datanálisis, migrating parents have left behind nearly 1 million children.

“You grow up fast,” said Fernández’s niece, Silvany, 9. Her mother went to work in Colombia in October.

Since then, Silvany and her cousins have remained with her ailing grandparents. And the fourth-grader has assumed many of the responsibilities for her little brother, Samuel, 1, feeding him and cradling him at night.

“I’m his sister,” she said, “but really I’m the nanny.”

In rare situations, children have been passed from grandparent to cousin to neighbor, with each caretaker migrating or disappearing, until young people finally have found themselves alone.

“This is a phenomenon that is going to change the face of our society,” said Abel Saraiba, a psychologist at CECODAP, which provides counseling to Venezuelan children. These separations, he added, have the potential to weaken the very generation that is supposed to one day rebuild a battered Venezuela.

The departures are overwhelming community organizations, many of which have seen their donors — middle- and upper-class families — flee the country just as they need them most.

The arrival of the new coronavirus in Venezuela has isolated these children further. To combat the spread, President Nicolás Maduro has announced a countrywide lockdown, sending the military into the streets to enforce the measures.

The effort has cut many young people off from the teachers and neighbors who may be their only means of support. At the same time, borders are now closed, severing these children from the rest of the world and making it impossible for their parents to return, or to come and retrieve them.

Here in the state of Zulia, where Fernández left her children in January, the economic collapse is particularly stark. It was once the Texas of Venezuela: rich in oil and cattle, proud of its distinctly regional culture and home to a flourishing class of petroleum workers who bought nice cars and took expensive vacations.

Today, it is home to rolling blackouts and jobs with monthly wages that barely buy two days’ worth of rice.

Down a wide street here in the state capital, Maracaibo, sits a modest building, painted blue, called Casa Hogar Carmela Valera.

It is a boarding school for girls in need, run by cheery nuns who swish down its sunny hallways in long black habits. In the past, students came here after parents died or began to use drugs. Today, at least half of its residents have a parent abroad.

The girls share a peach-colored bedroom, a kitchen, a chapel, a small mess hall and patio with a basketball court and a stage.

The school has seen better times. It has running water for a short period about every two weeks, and the girls shower, cook and flush the toilet using water they save in any containers they can find. They have no light bulbs for one of their two bathrooms, which means they brush their teeth on slippery floors in the dark.

Sister Wendy Khalil, 39, said that the home is desperate for everything: antibiotics, shampoo, toilet paper, vegetables, water tanks.

But her biggest concern is providing a degree of normalcy for her charges, keeping them busy with homework assignments and the occasional movie night so that they don’t have time to think about anything else.

Several of Fernández’s children had been remarkable students, she said, particularly Jean Carlos, an aspiring doctor who began to read around age 3.

Since she left, though, some of them have regressed significantly, especially Crisol, who had learned and then suddenly forgotten her multiplication tables.