Totally the mother’s fault.
Terrible situation for the zookeeper. But he had literally seconds to decide, and he chose to do the thing that would guarantee the safety of the child - which was the right choice. A tranquilizer would have taken too long, and the gorilla might have decided any pain it felt was coming from the kid.
Totally the mother’s fault.
There is no telling what the gorilla would have felt or thought. Killing it was the right call, but tragic, nonetheless.