Panic erupted at the San Diego Zoo after a 400-pound gorilla named Denny shattered a glass wall of his enclosure in front of stunned visitors.

Screams erupted and panic swept through the San Diego Zoo on Saturday afternoon when a 400-pound gorilla named Denny suddenly charged at the glass barrier of his enclosure, shattering a protective layer in front of stunned visitors.

The terrifying moment unfolded in the zoo’s popular Gorilla Forest habitat, where families gathered to observe the western lowland gorillas.

What started as a peaceful visit turned into chaos within seconds as Denny, a 10-year-old adolescent male, barreled toward the viewing window and slammed into the glass with explosive force.

“It literally felt like an earthquake before we realized it was him hitting the glass,” recalled Jackie Doubler, who was visiting with her family. “It was so loud, and then you saw the crack spreading out from where he hit—it was terrifying.”

Video footage captured by visitors shows Denny sprinting across the habitat, then launching himself into the thick pane of tempered safety glass.

A thunderous bang echoed across the exhibit as the impact caused spiderweb-like fractures to spread across one layer of the enclosure’s triple-layered protective wall.

Shrieks of panic filled the air as parents instinctively grabbed their children and bolted away from the window. Some zoo patrons reportedly ran in all directions, while others stood frozen in shock.

A few onlookers, perhaps unaware of the potential danger, even inched closer to inspect the damage.

“If he’d hit that glass again, I honestly think it would have been a whole different story,” Doubler added. “Everyone was on edge. Nobody expected that.”

Zoo security rushed to the scene within moments. According to a statement from the San Diego Zoo, Denny was not injured in the incident and no guests were harmed.

The glass wall, designed with three layers of tempered safety material, remained structurally sound despite the outermost layer being compromised.

As a precaution, Denny and his enclosure companion were relocated to an off-exhibit holding area while repairs are underway. The habitat has since been temporarily closed to the public.

Though the sight of a 400-pound gorilla slamming into glass was enough to send chills down the spines of many, zoo officials say the behavior was not entirely unexpected.

“Adolescent male gorillas like Denny often exhibit what we call ‘charging displays,’” a zoo spokesperson explained. “These displays—running, chest beating, dragging objects—are typical behavior and part of their natural social development.”

Experts suggest the situation may have been fueled by crowd stress or overstimulation. At 10 years old, Denny is entering a volatile stage of gorilla adolescence, where testing boundaries is part of instinct.

Dr. Erin Riley, a primatologist and professor of anthropology at San Diego State University, said displays like this are how gorillas communicate dominance or discomfort—especially when they feel observed or threatened.

“Gorillas don’t like direct eye contact. It can be perceived as a challenge,” Riley said. “If people are gathered closely, staring, tapping the glass, or making loud noises, it can become overwhelming, and they may respond with an aggressive display.”

Some visitors say they noticed children and adults knocking on the glass or trying to get the gorilla’s attention just moments before the incident. Others described the area around the habitat as being unusually crowded that day.

“They’re super strong animals. We need to be respectful of them and their space,” said Andrea Corry, who was also present during the event. “A lot of people hit the glass or try to provoke them. That’s not okay. You’re in their home.”

Saturday’s shocking scene comes just weeks after Denny experienced what some believe may be a traumatic loss—the sudden death of his older brother Maka, a 30-year-old silverback who died in August from a cardiac event.

The bond between gorilla siblings is often deep, and it’s possible Denny is still reacting to the loss.

While zoo officials have not directly linked the incident to Maka’s passing, experts say emotional stress in gorillas is very real.

“Gorillas grieve. They feel loss. We see changes in behavior when a family member dies,” said Dr. Annie Petersen, an animal behavior and bonding expert.

“This could’ve been an emotional outburst, or it could have been a young male testing his environment. Either way, it doesn’t appear to be a direct act of aggression.”

Western lowland gorillas are known for their immense strength—adult males can lift nearly ten times their own body weight—and while attacks on enclosures are rare, glass reinforcements at zoos are designed specifically with their strength in mind.

The triple-layered design at San Diego Zoo ensures that even if the first pane breaks, the interior remains sealed.

“There was never any real danger of escape,” the zoo’s statement emphasized. “The enclosure performed exactly as intended.”

Still, the moment left a lasting impression on those who witnessed it.

“You never forget something like that,” said Corry. “We come here thinking we’re safe behind the glass, and then you see it crack. You realize how powerful these animals really are.”

Despite the scare, zoo officials are reassuring the public that the safety of both guests and animals remains a top priority. Engineers are currently assessing the enclosure, and plans are underway to reinforce the damaged section.

Denny and his companion will remain off exhibit until the repairs are complete and all safety standards have been met.

Western lowland gorillas are a critically endangered species, native to the dense forests of central Africa.

Deforestation, poaching, and disease have decimated their wild populations. Facilities like the San Diego Zoo play a vital role in their conservation and education efforts, helping to foster appreciation—and respect—for these incredible creatures.

As for Denny, caretakers say he is in good health and showing no signs of distress following the incident. Zoo staff continue to monitor his behavior and provide enrichment as he adjusts to his temporary surroundings.

“We always want guests to feel safe, but also to understand that these are wild animals,” one staffer noted. “Respect is key.”

The Gorilla Forest is expected to reopen later this month once repairs are complete. Visitors are encouraged to observe posted guidelines and avoid tapping on the glass or making sudden movements near exhibits.

“Watch them, learn from them—but don’t provoke them,” said Doubler. “Denny gave us a wake-up call. Let’s not ignore it.”