5 Philadelphia Zoo Meerkats Die from Accidental Poisoning Suspected to Be Linked to Dye at Zoo

The animals all began showing signs of acute illness minutes after the dye, used to help with identification, was applied, according to the zoo

The Philadelphia Zoo is mourning the loss of five of its beloved residents.

A group of meerkats — named Lula, Nkosi, Nya, Kgala, and Ari — died suddenly at the zoo last week from exposure to an unknown toxin that zoo officials believe came from a dye that's routinely used to mark animals to differentiate them, the zoo confirmed to PEOPLE.

According to Amy Shearer, chief experience officer, the zoo has used the topical dye, called Nyanzol-D, for more than 30 years without incident, including on small primates. The dye was used on the meerkats on June 1, and one of them, Nkosi, was found dead roughly 30 minutes later.

An investigation into the meerkats' deaths to determine what was responsible for the poisonings is currently being conducted with the Association of Zoos and Aquariums and the U.S. Department of Agriculture. While the zoo waits to determine the cause of the poisonings, the facility has suspended using the topical dye Nyanzol-D.

Related: L.A. Zoo Welcomes 4 'Energetic' Meerkat Pups — and They're Already Busy Digging

The four others began showing signs of acute illness just minutes after, including vomiting black matter, prompting veterinary staff to anesthetize them and pump their stomachs, according to ABC News. However, three of the meerkats died within 36 hours despite the life-saving efforts. The last one, Shearer said, initially showed signs of recovery but died Monday night after spending more than a week under close medical supervision.

"It all happened very quickly and was so traumatic and tragic. Now we're trying to assess and doing a deep fact-finding process," she added. "We want to get to the bottom of it."

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The meerkat exhibit will sadly remain empty, as the deceased animals were the zoo's only meerkats. A sign was posted at the exhibit informing visitors of the situation, and according to Shearer, the news was met with shock and sadness by the public.

The meerkats' trainers have taken the loss particularly hard, she added. "The whole staff is devastated. The keepers are so close to the animals. They spend more time with these animals than their own families," she told PEOPLE.

The meerkat quintet arrived at the zoo as a group of siblings in 2013 and quickly became a popular attraction for visitors, thanks to their playful antics.

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Read the original article on People.