An "extremely intoxicated" 21-year-old woman was taken to hospital after entering the elephant pen at Denver Zoo and receiving a shock from the electric fence on Tuesday.
The zoo released a statement to 9 News, saying: "No animals were in the yard at the time."
"The woman was transported for medical care. Denver police and Denver Zoo are talking to guests to determine what happened."
According to Examiner, the woman was identified as Kelly Flynn. She had wandered away from a crowd at the zoo during its Christmas light event.
The Toyota Elephant Passage exhibit is designed to house eight Asian bull elephants, as well as one-horned rhinoceros, clouded leopards, Malayan tapirs and fishing cats.
The woman was treated for minor injuries and was charged for trespassing.
Shocking video: Circus worker dances on elephant as she dies
British tourists accused of breaking into theme park to steal penguin