CHICAGO (CBS) — The frightening incident involving a gorilla and young boy at the Cincinnati Zoo brings to mind a moment 20 years ago in Chicago–with a much different outcome.

In Cincinnati, zoo officials shot and killed a gorilla after the animal grabbed a young boy who had gotten inside the exhibit.

After an incident at Brookfield Zoo 20 years ago this summer, a boy, now in his early twenties, owes his life to the maternal instincts of a gorilla named Binti Jua.

It happened on Aug. 16, 1996, in the days before everyone had a cell phone that could capture video. Yet someone did record the moments after the child got away from his mother and fell into the ape pit at Brookfield Zoo.

The child lay lifeless for a few minutes until Binti Jua, then 8 years old, gently picked up the unconscious boy and cradled him in her arms, then handed him over to zoo keepers.

The boy was taken to Loyola University Medical Center and made a full recovery.

Binti Jua, with her own baby on her back, picked up the child and carried him to safety. Workers who were there said it’s an image they will never forget.

“She was somewhat protective, too. Part of the video, she takes the child and sort of turns a shoulder to the other gorillas,” zoo worker Jay Peterson said.

The story and images were carried around the world, making Binti Jua an international sensation, and a hometown hero to many.

Meantime, the prosecutor’s office says police are investigating the circumstances surrounding a 4-year-old boy entering a gorilla’s exhibit at the Cincinnati Zoo on Saturday.

The Hamilton County prosecutor’s office said Tuesday that police will confer with prosecutors after their investigation is complete.