The highest number of undocumented migrants one south Texas nonprofit welcomed in one day: 2,000. And a good portion of them tested positive for COVID-19.

To respond to the influx, a Mission, Texas, public park is now a quarantine site.

For two weeks, Anzalduas Park is where migrant families go to be tested for COVID-19 and to quarantine if necessary.

Anzalduas Park in Mission, Texas, was converted into a COVID-19 testing and quarantine area. (Ashley Soriano/Fox News)

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"Once we reached 2,000, there was something that I said because of COVID, we need to isolate, keep safe and away from everybody else," said Sister Norma Pimentel, executive director of the Catholic Charities Rio Grande Valley.

Catholic Charities RGV’s respite center in McAllen, Texas, is one stop along the migrants’ journeys. The previous site was a hotel, but with 2,000 people arriving, the center was moved to the park for more space.

Catholic Charities Respite Center itself can provide shelter for around 1,200 people.

"More than half of what we’re seeing, of 2,000 people, a 1,000 or more are children," Sister Pimentel said.

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Migrants arrive to the COVID-19 quarantine camp and testing center at Anzalduas Park in Mission, Texas. (Ashley Soriano/Fox News)

Two of those children include migrant Ingrid Cal’s 3.5-year-old and 4-year-old, who were sick along the 17-day journey from Guatemala.

"It’s difficult because the kids were sick. We fear for the kids’ safety crossing through Mexico but with God’s help we made it here," Cal said.

Pregnant women like Mariela Osorio from Honduras are also taking the risk. Osario, who eight months along, said, "I’ve heard of women being abused, but thankfully nothing has happened."

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Cal and Osorio will likely end up at Anzalduas Park to be tested for COVID-19. Even if only one person in a family tests positive, the entire group will remain at the park.

"When people visit, they can’t tell. They don’t see immigrants on the streets, people lying on sidewalks," said Roy Rodriguez, the city manager of McAllen. "That’s because we’ve gotten pretty good at this operation."