Immigration activists are calling for change after the death of an 8-year-old girl who died in Border Patrol custody in Harlingen.

The death of Anadith Danay Reyes Alvarez happened nine days after she crossed the border near Brownsville with her family.

Dozens of supporters from the ACLU, Arise, LUPE and Border Workers United held a vigil Tuesday at Hope Park in Harlingen to honor not just Alvarez, but the 13 children who’ve died in Border Patrol custody since 2010.

“I got grandkids and when you think of it, it shouldn't have happened,” activist Mario Reyes said, adding that Alvarez was being treated for flu-like symptoms prior to her death. “She was known to have had a medical history of heart condition. I think once CBP was aware of that their focus should have been to elevate the services and attention to her being as she was only a child."

Alvarez had heart surgery at the age of five, but her parents said she had been in stable condition since the procedure while needing continuous care from a cardiologist.

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On Sunday, May 14, the mother of the girl was seen being taken to a treatment area after complaining of abdominal pain, nasal congestion and cough. She tested positive for Influenza A, while Alvarez was given different medication for her symptoms.

On Wednesday, May 17, Alvarez and her mother were taken to Harlingen Medical Center three times. Alvarez was then taken to Valley Baptist Medical Center in Harlingen, where she was declared dead.

Justice of the Peace Precinct 3 Place 1 Judge Chuy Garcia ordered an autopsy. Garcia told Channel 5 News that preliminary autopsy reports show there were no findings of trauma, but the medical examiner did find some evidence of natural disease, which required further studies.

CBP continues investigating the death.