Last Friday, several western lowland apes — which can weigh as much as 270 kilograms — got into what is known as the gorilla kitchen from their enclosure in the rainforest exhibit.
The zoo says a review of what happened determined a keeper, who received a minor injury during a confrontation with one of the gorillas, failed to properly latch a door.
"There could have been terribly tragic consequences," said curator Malu Celli. "The keeper responsible no longer works at the zoo.
"We are happy that our protocols were in place in terms of our emergency response team and the team acted very quickly so the keeper only received minor injuries."
She said the decision to dismiss the zookeeper was difficult.
"It's a very difficult decision for the team and we just have to put the safety of our animals, our staff and the public very seriously," she said.
"It hasn't been an easy day."
The zoo has eight of the gorillas, which are native to central Africa.
The kitchen is attached to the enclosure and is filled with food gorillas eat, including fruit, fresh vegetables and grain. The animals who made for the munchies were safely moved back to the exhibit.
Celli said the gorillas are incredibly strong, even those who are young, and can be dangerous if they feel threatened. She said the animals inside the kitchen were in unfamiliar territory and were somewhat agitated.
There is no room for error when it comes to dealing with dangerous animals, Celli continued.
"For all of the animals in the zoo that are considered to be dangerous, the staff working there go through very intense training. We tend to only have senior staff who have been in the zoo for several years," shesaid.
"You do need to have the diligence and the attention to safety because you are putting your life and the lives of your co-workers and potentially the animals at risk."
No breaches in emergency response have been found so far, Celli said, but a review will continue to see if there are any ways to improve safety procedures.
This wasn't the first time the big primates have caused problems at the zoo.
In 2009, a western lowland gorilla named Barika made international headlines when it was photographed holding a knife that a zookeeper had left in the exhibit. Barika eventually lost interest in the knife and placed it on a chair, where it was safely recovered. No people or animals were injured.
A report by the Canadian Association of Zoos and Aquariums into the knife-wielding gorilla cleared the zoo of any wrongdoing.
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