Walking around a zoo is a great way to learn more about wild animals you'd never usually see in-person, as well as their native environments.
Yet nearly every single one of us has, at one point or another, wondered what would happen if an animal resident got out of its enclosure. Being at the zoo is kind of like being on a plane - you don't want to think of an emergency occurring, but you'd like to have some idea of your exit points in case it does.
The seemingly-unlikely occurrence of an animal escaping does actually happen though. It doesn't happen very often, but when it does, it causes widespread panic in concern for both the escapee and the welfare of people in the area.