(CNN) The 12-year-old wore a pink Disney princess backpack that said, "We Can Do ANYTHING," as she hugged her mom for the first time in eight months.

It was a moment Vilma Carrillo feared would never come.

"I held her so tight," Carrillo said, describing the recent reunion in a phone interview with CNN on Tuesday. "We stayed there a while, crying."

Advocates have been fighting to draw attention to Carrillo's case for months, warning that Carrillo, 38, could be at risk of losing her parental rights even though she was doing everything she could to reunite with her child.

Her story made national headlines and drew the attention of Hollywood actor Penn Badgley, who met with Carrillo inside an immigrant detention center in December and shared her story on Instagram

Carrillo's supporters got good news on Friday: Immigration and Customs Enforcement had decided to release Vilma from custody and fly her to Phoenix to reunite with her daughter, 246 days after officials separated them at the border.

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A spokesman for the agency could not be reached to speak about the case because of the partial government shutdown.

Officials didn't give Carrillo's lawyers any reason for her release, said Shana Tabak, executive director of the Tahirih Justice Center in Atlanta.

"That it should take eight months of advocacy and litigation to reunite them, that to me is really the story here. We and our partners really made a Herculean effort on behalf of this family to get the government to do the right thing," Tabak said. "That to me is really sad, because we don't know how many other families are separated in this way."

US immigration authorities separated Carrillo from her daughter, Yeisvi, after they crossed the border together in May 2018. But even though a federal judge last year ordered the US government to reunite most of the immigrant families it separated , advocates said this mother and daughter weren't covered by that ruling.

That's because Carrillo was born in Guatemala, but her daughter was born in the United States. Because Yeisvi is a US citizen, she couldn't be reunited with her mother in immigrant detention, as other parents and children were.

Instead, the daughter was placed in foster care in Arizona, and the mother was taken thousands of miles away to an immigrant detention center in Georgia.

Since US District Judge Dana Sabraw's June ruling in the American Civil Liberties Union's family separations case, officials have reunified more than 2,100 children with their parents, according to court records. But that tally doesn't account for any parents who, like Carrillo, were separated from children who are US citizens.

Tahirih, which is representing Carrillo, and the Southern Poverty Law Center, which filed appeal paperwork in an earlier stage of her case, shared photos this week of the mother and daughter's airport reunion.

The image was inspiring to advocates across the country who have been trying to help Carrillo, said Elizabeth Matherne, a senior lead attorney for the Southern Poverty Law Center's Southeast Immigrant Freedom Initiative.

"It is a bright spot in some very dark work," Matherne said.

Details of Carrillo's case came to light after volunteers with the SPLC pro bono project met with her. But there's no right to government-appointed counsel in immigration court, and many detained immigrants never have a chance to meet with lawyers and end up representing themselves. It's unclear how many others may be in the same situation as Carrillo.

"This case is emblematic of what happens in the shadows every day. If we found this one, Vilma, a week before her appeal is due, there's 10 more that we didn't find," Matherne said. "But that's why we're here on the ground. That's why we're screening people as quickly as we can."

The mother and daughter's reunion was a joyous moment, Tabak said, and the Arizona dependency case that threatened to take away Carrillo's parental rights has been dropped. But the legal battle is far from over.

"Vilma has a long road ahead of her still," Tabak said. "She needs to fight for her life in immigration court."

Carrillo said she fled domestic violence in Guatemala and is afraid to go back. A judge denied her asylum claim last year. Carrillo is appealing.

But for now, she's focused on enjoying time with her daughter -- doing everyday things like eating side by side and washing her hair.

"She doesn't want me to go outside," Carrillo said. "She's always holding my hand."