A woman died while in U.S. Border Patrol custody in Harlingen on Monday.

The 29-year-old woman was encountered with her family in the Rio Grande Valley sector on Sunday night and was in custody for less than 20 hours total, according to a statement from Customs and Border Protection.

CBP says the woman experienced a medical emergency while in custody and was treated onsite by a medical team. Emergency Medical Services were called to the station and transported the woman to a local hospital, where she was pronounced dead.

"Consistent with CBP protocol, the Office of Professional Responsibility is conducting an investigation of the incident," CBP said in the statement.

No other information was made available Tuesday afternoon.