The Philadelphia Zoo recently launched an investigation after five of its meerkats mysteriously died. It's believed the meerkats could've been poisoned.

The zoo took to Facebook to announce the tragedy in a post shared on June 16.

Photo: Flickr.com/Michael Stokes License: CC BY 2.0

"We are devastated to share that our meerkat siblings, Nkosi, Lula, Nya, Kgala, and Ari, have passed away. On June 1, our keepers noticed unusual behavior among the meerkats and immediately notified our veterinary team. Despite their valiant efforts, all five passed away within the last two weeks," they wrote.

They added that they've partnered with the U.S. Department of Agriculture and the Association of Zoos and Aquariums on a "fact-finding probe to uncover the direct cause of death."

https://www.facebook.com/philadelphiazoo/posts/657249096431006?ref=embed_post

The necropsy results are pending, but zoo leaders are looking into the possibility that the meerkats were accidentally poisoned with an animal-marking dye that's been used to differentiate near-identical meerkats for decades.

To be safe, the zoo has stopped using the dye until the necropsy results are in and the cause of death is officially determined.

According to ABC 6 News, Rachel Metz, the zoo's Vice President of Animal Wellbeing, said that both visitors and staff alike are devastated by the loss.

Photo: Pexels/Mike Bird

She said of the meerkats, "They are very popular, very charismatic animals with individual personalities. Our staff spends more time with these animals than they do with their own families or even their pets at home. So there's a real legitimate bond they feel with the animals, and obviously, they’re devastated right now."

According to a comment by the Philadelphia Zoo, the meerkat family has been at the zoo for the past decade. They said, "In 2016, we opened Meerkat Maze, an extension of our Zoo360 trail system, which allowed them to explore, dig and play together outside, delighting staff, volunteers and guests alike. We will miss them terribly."