Three snow leopards have died of COVID-19 at the Lincoln Children’s Zoo in Nebraska, officials say. It follows the death of another snow leopard at a South Dakota zoo last month.

“It is with deep sadness that we inform our community that three snow leopards at the Lincoln Children’s Zoo have passed away due to complications of COVID-19,” the zoo said in a statement. “This loss is truly heartbreaking, and we are all grieving together.”

Last month, a snow leopard at the Great Plains Zoo in South Dakota also died of coronavirus.