Three snow leopards have died at the Lincoln Children's Zoo in the US state of Nebraska of complications from COVID-19.
The zoo made the announcement in a Facebook post on Saturday, describing the deaths of the three leopards - named Ranney, Everest, and Makalu - as "truly heartbreaking".
The zoo began treating the leopards and two Sumatran tigers for the virus last month.
The tigers, Axl and Kumar, had made a recovery.
The zoo said it remained open to the public and continues to take precautions to prevent the spread of COVID-19 to humans and animals.
Zoos across the country, including at the St Louis Zoo and the Denver Zoo, have battled outbreaks among their animals.