The morning sky is brightening to pale blue when the four Hernandez children leave the safety of the Church of the Advocate and file into a waiting Ford van.

Their mother stays behind. And when the last door shuts, the kids turn quiet.

They aren't alone for the ride. An adult friend is driving, and another comes along for support. So does a city councilwoman.

But their first day of school is different from those of other students, their jitters about a new term fused with uncertainty over what could happen in the next half-hour.

All four — Edwin, 9; Yoselin, 12; Keyri, 13; and Fidel, 16 — face standing deportation orders, as does their mother, Carmela Apolonio Hernandez. For nearly 10 months, they've lived in sanctuary in the North Philadelphia church, blocking a forced return to Mexico that Hernandez says could get them killed by gangsters.

For these four children, heading to school does not mean a brisk stroll across city sidewalks or hanging with friends at the bus stop.

It's 25 minutes of exposure and vulnerability, a risky ride from church to school in a city where federal immigration authorities are especially aggressive, in a country where the government is detaining and deporting undocumented people.

If agents were going to move against the children, the streets would be a place to do it.

"I'm a little nervous leaving sanctuary," Keyri says, "but I'm sure everything will be OK."

Risk of deportation part of life

Somewhere down the block from the Episcopal church, the chug of an idling school bus breaks the Monday morning calm. The streets around 18th and Diamond Streets begin filling with traffic and Temple University students.

Gathered outside a church door, waiting to join 200,000 students headed to school in Philadelphia, the siblings talk about class schedules and favorite subjects. Keyri half-dances across the concrete, then playfully smacks Yoselin on the shoulder. Fidel stretches. Edwin holds close to his mom.

"Being at risk of deportation," Hernandez says, "is part of their lives. They know they have to go on and live their lives…  They tell each other not to be afraid."

The family came to America in 2015, after Hernandez and her eldest daughter were assaulted by the same drug criminals who murdered her brother and two nephews. In mid-December, with their petition for asylum denied and deportation imminent, Hernandez took her family into sanctuary.

In the meantime, she says, her children's lives can't stop while the family presses its legal case.

Hernandez, 37, sent the children to school in January, asserting their right to education and challenging Immigration and Customs Enforcement, known as ICE. The Philadelphia school system has been welcoming and has followed the law, which guarantees public education to all children, regardless of status.

Fidel and Keyri attend one school, Edwin and Yoselin another. The challenge is getting there. (The Inquirer and Daily News agreed not to name their schools as a condition of traveling with them.)

While ICE guidelines dissuade agents from taking action at designated "sensitive locations," such as churches, schools, and hospitals, the agency asserts the right to detain undocumented immigrants anywhere, anytime.

Arrests have occurred near churches and schools, if not on the grounds, and agents have stopped cars and detained undocumented immigrants riding inside.

A spokesperson for the agency declined to comment on the children's return to school.

Philadelphia is a "sanctuary city," where the local government strives to treat undocumented immigrants the same as everyone else. But that offers no protection from federal authorities, who arrested 156 undocumented migrants during two sweeps in September and May.

>>READ MORE: In Philly and across the nation, more immigrants take church sanctuary to block deportation

The Hernandez family, supporters say, has two advantages: the publicity surrounding their life in sanctuary and the backing of elected officials.

"Visibility and public support act as a shield," said Jasmin Delgado, a leader of the Sanctuary Advocate Coalition, which formed to help the family. "It's in the shadows that ICE acts with impunity."

Two facts about sanctuary: It's hard on people who claim it. And it can work.

Javier Flores Garcia spent almost a year inside Arch Street United Methodist Church in Center City, walking free in October 2017 after being granted "deferred action." That status allows him to live in the United States while awaiting a visa.

Last week, a Colorado woman ended 10 months in sanctuary after being assured by ICE she was not a priority for deportation to Mexico. Sandra Lopez's departure followed a Supreme Court ruling that opened a new route for her to pursue legal status.

>>READ MORE: In an ICE lobby in Center City, a microcosm of immigration battles

Hernandez's children have briefly left the church at times. Keyri has spoken at public, pro-immigrant rallies. And on Friday, all four met with Democratic Sen. Bob Casey at his Philadelphia office, asking him to help their family.

Hernandez is confined to the church.

Lately, she's been sick — with allergies, headaches, joint pain, an ear infection. Some illness might be caused by stress, she said. She sees her children growing up and older in sanctuary.

On the way to school, excitement and uncertainty

The van heads south and then east, past rowhouses, past children walking to school, past people for whom the ability to roam is a given.

In a back seat, Councilwoman Helen Gym, an ally from the start, talks with Delgado about what the children may need from the School District, such as translators. If the siblings are harassed in any way, Gym says, Delgado should contact her immediately.

Fidel and Keyri are first to be dropped off, and Gym and Delgado go inside, too, to make sure all is well. Fifteen minutes later, the van pulls over again, and Edwin and Yoselin hop out, eager to start the day.

The morning ends with all four safely in class.

The plan for coming weeks is for the children to travel by school bus, boarding directly outside the church and exiting at the doors of their schools. A team of advocates will be on call, ready to move quickly to the children if the bus breaks down or meets trouble.

Hernandez's children say that they've made friends at school. That they look forward to the time when going to class won't mean taking a risk. When they can legally live in America.

"I have a birthday wish," says Keyri, who turns 14 next Wednesday. "To no longer be in sanctuary when my birthday comes."