The park says two dogs were loose on the zoo's property and one of them somehow managed to get inside the enclosure.
It's not clear exactly how that happened, but the gorillas appeared to be agitated by the intrusion as they chased the dog, as seen in video captured by people at the park.
Specialists at the park were eventually able to recall the gorillas out of the habitat so that the dog, now named "Mighty Joe Young," could be rescued.
No animals or people were hurt. The two dogs are now being cared for at the San Diego Humane Society.