Animal expert Jeff Corwin has urged parents to keep a close eye on their children at zoos following Saturday’s incident at Cincinnati Zoo that resulted in the death of a silverback gorilla.

The 400-pound animal was shot after a 4-year-old boy fell into a moat where the gorilla was housed. Zoo officials are standing by their decision to kill the gorilla, noting that that the boy was in danger. Animal rights groups, however, are expressing outrage over the killing of the 17-year-old gorilla.

Conservationist and TV host Corwin told Fox 25 that the tragic incident highlights the need for parents to be vigilant at zoos.

“Zoos aren’t your babysitter,” he said. “Take a break from the cellphone and the selfie stick and the texting, connect with your children, be responsible for your children.”

Related: Zoo that killed 400-pound silverback Harambe to protect boy 'stands by decision'

The male silverback gorilla, named Harambe, was “clearly agitated and clearly disoriented” and “acting erratically” Thane Maynard, director of the Cincinnati Zoo and Botanical Garden, said at a press conference Monday.

Video of the incident shows the boy being dragged by Harambe. The boy was being dragged around and his head was hitting the concrete, Maynard said.

Witness Kim O'Connor told WLWT-TV she heard the boy say he wanted to get in the water with the gorillas. She said the boy's mother was with several other young children.

After the child fell into the area that houses the primates, the zoo’s gorilla trainers gave the animals a special signal that calls them back inside. Maynard said while the female gorillas responded to the call, Harambe was distracted by the events and did not respond.

Related: Cute zoo babies

Maynard said that officials did not take killing Harambe lightly and that his death was “a big loss” for the gorilla’s trainers and the entire zoo family.

Jack Hanna, Director Emeritus of the Columbus Zoo and Aquarium, told Fox and Friends that Cincinnati Zoo had no choice but to kill the gorilla. “What they had to do, had to be done,” he said.

Hanna explained that silverback males are so powerful they can take a green coconut and “squish it like a marshmallow.”

The zookeeper said that using a tranquilizer dart to sedate the gorilla would not have been an option given the danger the 4-year-old child was in. “It takes 5 to 10 minutes for the gorilla to go to sleep,” he said. “There was not a millisecond to waste on this.”

Related: 7 cool shots of African animals

Corwin told Fox 25 that the silverback gorilla is “incredibly endangered,” noting that the gorillas are “on the precipice” of extinction. “No amount of money or biology or science can ever bring back what was lost with the death of this gorilla,” he added.

Such is the extent of the media attention focused on the gorilla’s killing, that even presumptive Republican presidential nominee Donald Trump was asked about the incident during a press conference Monday. “I don’t think they had a choice,” he said, noting the gorilla’s immense power. “It just takes one second – it takes one little flick of his finger.”

Since the gorilla's death, the hashtag #JusticeForHarambe is trending on Twitter and a petition has been launched calling for "the parents to be held accountable for the lack of supervision and negligence that caused Harambe to lose his life.”

"This beautiful gorilla lost his life because the boy's parents did not keep a closer watch on the child," the change.org petition reads.

The family of the boy released a statement Sunday that the boy was home and doing fine.