HARLINGEN, Texas (AP) — An 8-year-old girl died Wednesday in Border Patrol custody, authorities said, a rare occurrence that comes as the agency struggles with overcrowding.

The child and her family were being held at a station in Harlingen, Texas, in Rio Grande Valley, one of the busiest corridors for illegal crossings, US Customs and Border Protection, the Border Patrol’s parent agency, said in a statement.

The girl experienced “a medical emergency” and was taken to a nearby hospital, where she died, according to the statement, which did not disclose her nationality or provide additional information about the incident.

Customs and Border Protection’s internal affairs office will investigate, and the Homeland Security Department’s inspector general and Harlingen police have been notified, Miller said. Sergeant Larry Moore, a spokesman for the Harlingen Police Department, said he had no information about the death.

The Border Patrol had 28,717 people in custody on May 10, the day before pandemic-related asylum restrictions expired, which was double from two weeks earlier, according to a court filing. By Sunday, the number had dropped 23 per cent to 22,259, still unusually high.

The average time in custody on Sunday was 77 hours, five hours more than the maximum allowed under agency policy.

Last week, the Border Patrol began releasing migrants in the US without notices to appear in immigration court, instead directing them to report to an immigration office within 60 days. The move spares Border Patrol agents time-consuming processing duties, allowing them to open space in holding facilities. A federal judge in Florida ordered an end to the quick releases.

Also last week, a 17-year-old Honduran boy travelling alone died in US Health and Human Services Department custody.