An adult male gorilla name Koga, who weighed more than 400 pounds, bit a zookeeper at the Buffalo Zoo after he escaped from his cage on Monday.

Koga, a 24-year-old silverback West Lowland gorilla native to West Africa and the Congo River Basin, reportedly broke through the unlocked door of his cage and entered the space behind it utilized by zookeepers called the animal keeper aisle, though closed to the public in a secure non-public area behind the gorilla exhibit, according to the zoo.

The gorilla then bit a female zookeeper while servicing the area, though her name has not been released, who had worked with him for almost five years when she tried to contain him.

He was probably just as surprised coming face to face with her as she was with him, Buffalo Zoo President Donna Fernandes said, as reported by Reuters.

The zookeeper sought out refuge in a habitat of a nearby 14-year-old female gorilla named Sidney and her one-and-a-half-year-old baby Amari while the 45-minute incident went down, where officials say she was safe and unharmed. She was sent to a nearby hospital and examined, though her ring hand and left cal injuries were not serious.

According to a SWAT team official who helped secure the area while a veterinarian sedated Koga, the experience was the most terrifying of his life.

That was the scariest thing I've ever done in my career, SWAT team captain Mark Maraschiello said according to Reuters. It's a 400 pound animal that's capable of who knows what. He could rip your arm out of its socket.

In this emergency situation, we experienced the best possible outcome thanks to the training and professionalism of the Buffalo Zoo staff, as well as members of the Buffalo Police Department, especially the SWAT team, Fernandes said in a statement.

Visitors at the Buffalo Zoo were escorted to an indoors refuge nearby and waited for 45 minutes while the gorilla was contained and put back in his cage 15 minutes after the drugs sedated Koga, administered through a handheld blow pipe. The Buffalo Zoo reopened to the public at 1:00 p.m.

Koga did not run rampant thanks to several other locked doors within the gorilla habitat.

The Buffalo Zoo is conducting an investigation as to how Koga, the 400-pound gorilla, escaped.

Koga was born in the Bronx Zoo and lived in the Memphis Zoo from 1994 to 2007 when he was transferred to the Buffalo Zoo, according to Reuters.