An investigation into the death of an 8-year-old Panamanian girl while in US Border Patrol custody in Harlingen, Texas, has found that the family was repeatedly denied access to an ambulance, US Customs and Border Protection (CBP) has said. 

The child died on May 17 after experiencing a medical emergency at the agency's station in Harlingen, three days after being transferred from the Donna Processing Facility, near the border in Donna, Texas, for medical isolation.

The child's mother said officials ignored repeated calls to hospitalize her daughter while they were in US custody.

"They killed my daughter, because she was nearly a day and a half without being able to breathe," the mother said. "She cried and begged for her life and they ignored her. They didn't do anything for her."

Acting CBP Commissioner Troy Miller called the child's death "a deeply disturbing and unacceptable tragedy" in a statement and pledged to take action — including banning some of the medical providers involved and investigating medically vulnerable people in the agency's custody.

The family was held by CBP for nine days, despite agency policy limiting custody to 72 hours.

Two US Department of Homeland Security officials said the family was facing deportation and spoke on condition of anonymity to discuss details of the case.

Neither Border Patrol agents nor contracted medical personnel who interacted with the family in Harlingen acknowledged that they were aware of the girl's medical conditions, which include sickle cell anemia and congenital heart disease, CBP said.

CBP said the family had reported the girl's medical history to Donna Center, adding that the girl's mother had requested three or four times that an ambulance be called or the child taken to a hospital.

The girl developed a fever that peaked at 104.9 degrees Fahrenheit (40.5 degrees Celsius) early on the morning of May 16, CBP said, adding that she was prescribed flu and fever-reducing medications, ice packs, and a cold shower.

"Despite the girl's condition, her mother's concerns, and the series of treatments required to manage her condition, contracted medical personnel did not transfer her to a hospital for higher-level care," the statement said.

Additionally, CBP said, surveillance cameras at the Harlingen station were not working while the family was in custody, forcing them to rely on staff interviews.

The agency said the latest details about the incident have come from an ongoing investigation by CBP's Office of Professional Responsibility and are still subject to confirmation.