A bonobo at the Cincinnati Zoo bit one of their care team member's thumb while they were delivering food and medicine to the troop, causing a "partial amputation," the zoo said in a statement.According to the zoo, it happened Friday morning when a member of the primate care team was behind the scenes at the Jungle Trails habitat, administering food and medicine to the bonobo troop.One of the bonobos bit the care team member's thumb "through a protective mesh barrier" as they were delivering medication and food, the zoo said.Initially, the zoo said the bite resulted in a "complete amputation" but later learned from the medical team that the care team member sustained a "partial amputation." They are receiving medical treatment and are in stable condition.No other staff, guests, or animals were involved or injured. "The Cincinnati Zoo prioritizes the safety of its employees and animals. Bonobos are highly intelligent and social primates, and interactions with them involve established protocols and safety procedures. At no time were the bonobos outside their habitat and per zoo policy, animal care staff and great apes do not occupy shared spaces," the zoo said in a statement.The zoo is working to understand what led to the incident and the Jungle Trails habitat will remain closed to the public Friday, officials said.