SAN DIEGO (FOX 5/KUSI) — A 10-year-old western lowland gorilla at the San Diego Zoo broke a layer of protective glass in its enclosure on Saturday, zoo officials confirmed.

According to a statement from zoo, the incident occurred on Oct. 11, when the gorilla, named Denny, broke through one of three layers of tempered glass that separates the animal from zoo visitors in the gorilla forest habitat. Another gorilla was also in the compound at the time of the occurrence.

“Denny was not injured,” the zoo noted. “Both gorillas will be cared for behind the scenes until the panel has been replaced.”

Zoo officials emphasized that the glass panel consists of three protective layers, and only one was compromised. No guests or staff were harmed during the incident.

The impact startled people who saw it happen.

“We were looking down at our cell phones and didn’t notice that he had taken a running start, jumped and launched into the glass. He hit it with his elbow or forearm, like right in the glass directly in front of my face,” said Katya Sutil, who was celebrating her birthday at the zoo with her sister. “When it hit in front me, I was so jolted I fell back a few feet. When I looked up to see what had happened, I saw the gorilla staring directly at me, making eye contact with me, and then a giant crack… 6 feet. It was pretty big.”

A timeline for when the gorilla habitat will reopen to the public was not immediately provided.

“Honestly, the 20 minutes we were there, the gorillas were going back and forth, kind of taunting each other. One would charge the other and then disappear, then it would happen again,” Sutil explained. “So maybe there was tension going on between the two gorillas.”

Western lowland gorillas, like Denny, are critically endangered species native to the forests of Central Africa. The San Diego Zoo is involved in conservation efforts to protect these primates and their natural habitat.

For more information, visit sandiegozoowildlifealliance.org/species/gorilla.