A northern white rhinoceros -- one of just four remaining worldwide -- has died at the San Diego Zoo, officials said.
The 41-year-old female known as Nola saw her health take a quick turn for the worse.
"Early this morning, the team made the difficult decision to euthanize her," the zoo said in a statement.
Watch "Racing Extinction" on Discovery Channel, Dec. 2, at 9 PM ET/PT.
The animal -- battling an infection and other age-related ailments -- had been at the zoo since 1989. It underwent surgery November 13 but then stopped eating shortly thereafter.
"Nola leaves a legacy that her keepers and animal care staff hope will continue to help rhino conservation for years to come," the zoo added.
The three remaining animals are at a conservatory in Kenya.