NEW YORK: A 400-pound adult male gorilla escaped his cage at the Buffalo Zoo on Monday, biting a female zookeeper before being tranquilized and captured in what a SWAT team leader called, "the scariest thing I've ever done."

Zoo officials said Koga, a 24-year-old silverback gorilla, took advantage of an unlocked door in his living quarters on Monday morning and slipped into the space behind it, used by zoo personnel but closed to the public.

A keeper who has cared for Koga since he arrived in 2007 was bitten on her hand and calf, in what officials said was an act of excitement rather than aggression.

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

The keeper, whose name was not released, took refuge inside the habitat of a female gorilla and her newborn baby, Fernandes said. The keeper had a good relationship with the mother who, like Koga, is a West Lowland gorilla, native to West Africa and the Congo River Basin, she said.

Meanwhile, police sent in the SWAT team to secure the area while a veterinarian used a handheld blow pipe to sedate Koga through a porthole.

Visitors to the zoo were moved indoors and stayed there throughout the roughly 45-minute ordeal -- the zoo's first escape, Fernandes said.

"That was the scariest thing I've ever done in my career," said SWAT team captain Mark Maraschiello.

"It's a 400 pound animal that's capable of who knows what. He could rip your arm out of its socket," Maraschiello said.

The sedated gorilla was dragged by zoo staff back to his habitat once the drugs took hold, about 15 minutes after they were administered.

The keeper's decision to lock herself inside the separate habitat likely kept her from being further harmed, according to officials at the zoo. Several locked doors kept Koga from running amok through the zoo and beyond.

Fernandes promised an investigation into how Koga escaped.

"I'm sure it was very dramatic for (the zoo keeper) and for all the keepers. It was pins and needles," she said.

The wounded zookeeper was undergoing an evaluation at a nearby hospital but her injuries were not considered serious.

Koga was born at the Bronx Zoo in New York City and transferred in 1994 to the Memphis Zoo before landing in Buffalo. Fernandes said he has no history of unusual aggression. AGENCIES