A zoo in a Philadelphia suburb is investigating the unexpected death of a young red panda.

The Elmwood Park Zoo in Norristown said the red panda, named Clinger, died on Nov. 29. An animal autopsy did not provide a cause of death, zoo officials said.

"Although only here a short time, Clinger made a definite impact among all of us that cared for him and all of you that came to visit him. He will be deeply missed," Elmwood Park Zoo said in a Facebook post.

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Zoo staff was "stunned" at the death, as Clinger showed no obvious signs of illness or distress, the zoo said.

Veterinarians examined Clinger's brothers, Shredder and Slash, and conducted blood work and x-rays, the zoo said. They found both animals to be healthy.

Now the zoo is waiting for results of a tissue analysis being conducted by a zoological pathologist to learn more about what may have caused Clinger's death.

"Our hope is that we will be able to share further details on what caused Clinger's passing when and if it is determined," the zoo said.

Red pandas typically live between 10 and 12 years.