EL PASO, Texas (KTSM) — El Paso County Sheriff Richard Wiles says a Sheriff’s detention officer was attacked by an inmate Thursday while returning from a medical appointment.

Wiles says it happened Thursday morning around 3:45 a.m. when a detention officer was transporting inmate Diana Herrera from University Medical Center, where she was being treated. According to Wiles, Herrera was with a female detention officer, who placed her in the vehicle’s rear. The officer left a window on the plexiglass partition open due to the unit’s high temperatures and lack of ventilation.

While driving down Montana Avenue approaching Joe Battle Boulevard, Wiles said Herrera slipped out of her shackles and lunged at the officer through the open window, and a struggle ensued. The officer was able to throw the vehicle into park to avoid an accident.

During the struggle for the officer’s duty weapon, Herrera managed to discharge the officer’s weapon close to the officer’s face, causing a lip injury. Wiles claims Herrera also hit the officer in the head with the butt of the gun and put her arm around the neck of the deputy.

An off-duty U.S. Customs Agent who was behind the EPCSO transport unit at the time of the alleged assault intervened and was able to subdue Herrera.

According to court records, Herrera was in custody since December 7, 2021, on Robbery and Aggravated Assault w/a Deadly Weapon charges. Wiles says the Sheriff’s Office has charged her with Criminal Attempt Capital Murder following Thursday’s alleged assault. Her bonds total $1,100,000.

The Sheriff’s office has not identified the deputy involved. However, they say she has been released from the hospital after receiving treatment for injuries sustained in the alleged attack.

Wiles also declined to identify the off-duty U.S. Customs agent who intervened.