EL PASO – As the high-stakes immigration debates rage nationally over walls, U.S. border troops, caravans and a federal government shutdown, crowded buses roll into the downtown Greyhound station on San Antonio street.

That's where hundreds of migrant asylum-seekers were sent after federal detention centers hit full capacity as more and more people squeeze into ill-equipped border stations.

El Paso's Annunciation House, an immigrant shelter that coordinates local migrant assistance efforts, is spending about $150,000 a month to rent all the rooms at four local motels to house migrants.

The "migrant hospitality center" network has expanded to 15 sites in El Paso and five in Las Cruces, New Mexico. Shelters vary in capacity from 15 to 100 people.

Shelters recently have been taking in about 2,200 to 2,300 migrants a week. The goal is to expand the network to be able to accommodate 3,000 migrants per week, said Ruben Garcia, executive director of Annunciation House.

U.S. authorities released more than 1,500 migrants this week in El Paso, including 522 on Wednesday, the largest single-day release.

“I am really, really disappointed when my government does things like this," Garcia said of mass releases earlier this week. "The bottom line is you don’t release families with young children to the streets.”

Advocates expressed concern that immigration authorities were rushing migrants through the asylum process following the deaths of two Guatemalan children this month who were in Customs and Border Protection custody.

Felipe Gómez Alonzo, 8, who died Christmas Eve, tested positive for influenza B, according to the New Mexico Office of the Medical Investigator.

Jakelin Caal, 7, also Guatemalan, died Dec. 8. at an El Paso children's hospital after being detained with her father and while preparing to travel by bus to a Border Patrol station in New Mexico.

The chaos at the border has also been complicated by the partial government shutdown over President Donald Trump's insistence on including funds for a border wall in the federal budget. The shutdown has particularly snarled attempts to get information from the key government agencies dealing with immigration and border security.

Secretary of Homeland Security Kirstjen Nielsen visited El Paso on Friday to see how the agency conducts medical screenings and to review conditions at Border Patrol stations following the two child deaths.

The scene in El Paso is being played out at many locations along the Texas-Mexican border as the flood of migrants from Central America seek asylum in the United States.

In Arizona, about 6,000 migrants have been dropped off since mid-October at a dozen churches in Phoenix, Mesa, Gilbert and Ahwatukee Foothills that house and feed migrant families before they travel to their next destination.

Most migrants are gone by the next day, jumping on another Greyhound bus or a flight to reunite with family members across the country. But the churches that host people remain overloaded.

"We need new facilities, additional facilities to open their doors, whether they be churches or community centers," said Susan Whetten-Udall, the LDS Immigrant Services Volunteer Coordinator who has been helping out in Phoenix.

Without way stations like Annunciation, says newly elected U.S. Rep.- Veronica Escobar, D-Texas, migrants who have been processed by ICE would end up on the streets of El Paso homeless, hungry and without support.

"The federal government has an obligation to provide humane, temporary holding facilities for these migrants in their custody until they can be accepted by NGOs like Annunciation House," Escobar said. "Quickly ridding themselves of those in their custody is not a solution. In fact, it puts adults and children at grave risk and creates a crisis in our community."

In October, ICE released more than 200 asylum seekers on the city streets after saying they could no longer hold them for more than a few days.

After the incident, Garcia said, ICE and Annunciation House had reached a verbal agreement that ICE would let the nonprofit know about upcoming migrant releases and check capacity at the migrant shelters. ICE would then drop off the migrants at shelters where space was available.

Garcia said he doesn't know why ICE decided to drop migrants at the bus station this week.

To meet the demand, volunteer centers have learned to mobilize on short notice. When the ICE buses showed up at the Greyhound station earlier this week, so did volunteers bearing food and clothing.

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On Monday morning, vehicles carrying the migrants who were brought in on Sunday trickled in to the bus station parking lot, dropping off families who had made contact with their relatives in the United States. Families, some with toddlers, walked into the bus station carrying their belongings in trash bags and reusable totes.

But by Monday afternoon, hundreds more migrants were being released at the bus station.

U.S. Rep. Beto O'Rourke, D-Texas, was at a park near the downtown station on Monday, helping hand out food to incoming migrants. Officials estimated about 170 migrants were dropped off while he was there.

O'Rourke said that he had spoken to the director of ICE, who told him the unannounced releases were mistakes. “ICE made a mistake yesterday," he said. "I don't think it was intentional. I think they made a mistake in not alerting the community.”

The El Paso Democrat championed the cause of migrants during his unsuccessful run for the Senate against Republican Ted Cruz that has boosted his national profile.

O'Rourke, who has been mentioned as a potential presidential contender, has kept himself firmly in the spotlight as the president and Democratic lawmakers battle over Trump's long-sought border wall and a hot debate over whether migrants represent violent invaders or are families fleeing poverty and violence in Central America.

As the migrant wave builds, Annunciation House has put out an appeal to the community asking for donations of fresh fruit, especially tangerines and bananas, as well as new clothing, particularly bras, underwear and socks in all sizes. They also sought volunteers "willing to drive folks to the bus station and airport."

Garcia said immigration holding facilities on the border were initially set up to hold men – not families.

"It's inappropriate to be holding families in holding cells. It created pressure on the part of ICE to release" migrants, Garcia said, adding that it has also placed pressure on groups like his to find shelter for released migrants.

Garcia added that he had heard that women, especially those pregnant, were being released due to crowding at the women's detention area of one immigration detention center in El Paso.

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In Arizona, ICE officials say the agency lacks the capacity to hold migrant families crossing the border daily in the southwestern part of the state. In response, they have begun releasing them to local churches in Phoenix and to nonprofits in Tucson and, for a while, in Yuma.

"What's happening now is the churches are at capacity or they're tapped out on resources," said Lydia Guzman, a Phoenix activist. “We’re trying to get new folks, a new network of churches to open their doors and provide services.”

Estela Tomas Felipe was one of the more than 1,500 migrants released in El Paso this week.

At the Greyhound station, Felipe, with her 1-year-old daughter strapped to her back, was in good spirits, freshly showered and wearing a new set of donated clothes. She was heading to Birmingham, Alabama, to meet her husband, who left Guatemala two months ago just after she became pregnant with their second child.

Despite the prospect of joining her husband, Felipe was not sure she would recommend the journey to people back home in her country.

She said she left a poor farming community in Guatemala 21 days ago. The typical work of harvesting corn, onions and fava beans is getting scarce.

There, "they take women and then they rape them or kill them," she said as she explained why she and her daughter made the harrowing trip by truck and other vehicles through Mexico and into the United States. "That's why I came here."