CINCINNATI (CBSNewYork)–  Dramatic new video is showing the horrifying moment when a 4-year-old boy went face-to-face with a 400-pound gorilla at the Cincinnati Zoo.

A mother tried to calm her young son down as the massive gorilla dragged him through the exhibit Saturday. The Cincinnati Zoo said the child climbed through the fence, CBS2’s Ali Bauman reported.

“The little boy himself had already been talking about ‘go in, go in, get in the water’, and his mother is ‘no you’re not, no you’re not,'” witness Kim O’Connor said. “I don’t know if the screaming did it or too many people hanging on the edge, if he thought we were coming in, but then he pulled the boy down further away from big group.”

The little boy was down 15 feet in Gorilla World for around ten minutes. The zoo said officials were forced to shoot and kill the 17-year-old Silverback, nicknamed Harambe, in order to save the child.

“I just want people to know he was not a vicious animal,” Jerry Stones, the animal’s caretaker, said. “He was just a young teenage boy who was put in a bad situation.”

Stones helped take care of Harambe for 15 years. The Western lowland gorilla is a critically endangered species. Stones believes the gorilla was scared and did not know what to do.

The zoo said Harambe did not comply when they called and a tranquilizer simply was not enough.

“In an agitated situation, which that was, it may take quite a while for a tranquilizer to take effect. But certainly in an incident when he would be hit, he would have a dramatic response. You don’t hit him and he falls over. It would take a few minutes,” an official said.

Parents at the Turtle Back Zoo in West Orange, New Jersey said they are watching children a little more closely today. Many said they are saddened by the gorilla’s death, but would do anything to save their child.

“I think it was really hard for zoo officials to make that determination, but I think they did the right thing,” one parent told CBS2.

“I would hope they wouldn’t kill the gorilla because it is half my responsibility just like it’s the zoo’s responsibility so I should keep a close eye on my children,” another said.

But in a worst case scenario, some parents are prepared to let their own animal instincts take over.

“Jumping into the pit right along with him,” one parent said.

The child was taken to the hospital and released last night.