One visitor got a close-up look at the gorillas in the San Diego zoo enclosure on Sunday - and it wasn't a member of staff.
Shocking video footage shows the moment a stray dog broke into the gorilla's habitat and was chased by a silverback, before being safely removed.
The incident was captured on video by visitors, who tried to call the gorilla by its name to stop it from potentially harming the dog.
The year-and-a-half-old male shepherd could be seen trying to escape Frank the gorilla as families rushed to alert zoo keepers.
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Bystander Robert Robles told CBS 8 : "They just started chasing after him and that was pretty nerve-wracking. A lot of employees showed up from the zoo and they literally kicked us out."
Staff explained the gorilla likely just wanted to scare the dog out of the enclosure, but they worried the situation would have escalated.
The dog could be seen panting and happily wagging his tail, then he began to run as Frank charges after him.
One person watching the incident unfold exclaimed: "That thing is fast."
After several near misses, the young pup managed to maintain a safe distance from Frank, while zoo keepers called both gorillas inside the enclosure.
The San Diego Humane Society then stepped in to safely rescue the dog.
Officer Samantha Clark told Fox News : "When I turned up at the gorilla enclosure, he did look very nervous and afraid.
"The dog probably felt like he was in the wrong place at the wrong time.
"You can tell he really wanted help because he wandered over with his tail wagging."
The shepherd was one of three stray dogs that ran freely into the park without an owner - but he was the only one flirting with possible disaster.
The San Diego Humane Society have since named the dog Mighty Joe Young, in honour of the film.
The team have taken him under their wing while they attempt to locate his owner, though without a microchip it is proving difficult.
Many people have since volunteered to adopt the homeless pup, including the San Diego zoo keeper who asked to keep him as her own.
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