The Toronto Zoo says a 17-year-old Sulawesi babirusa has died after an incident that appears to have involved human error.

The zoo says the babirusa, named Bucky, was fatally injured Saturday after getting into an area occupied by a male greater one-horned rhinoceros.

It says that despite staff’s quick response, they weren’t able to save Bucky.

The zoo says it has launched a full investigation into the incident, and early findings indicate human error played a role.