EL PASO, Texas -- A U.S. Customs and Border Protection drug-sniffing dog is left inside a unit by an officer and dies.

KFOX was able to confirm the statement with CBP officials last week. CBP officials said the incident happened on July 6, but won't release any other details.

A source tells KFOX that the CBP officer finished his overnight shift at one of the ports of entry and forgot to put his dog back in the kennel.

The source said the dog was left inside the vehicle from 8 in the morning until 4 in the afternoon, when he was found dead.

KFOX talked to a local animal advocate who said a service dog is supposed to be an officer's partner.

"The natural temperature for a dog is 102 degrees. At 104 degrees, the animal is gonna go into cardiac arrest and cause severe brain damage. The temperatures are going to rise in the cabin of a vehicle within 10 to 15 minutes," said Rebecca Rojas, a local animal advocate.

CBP officials said immediate steps were taken to ensure that a similar incident will not be repeated.