A 400-pound (180-kilogramme) gorilla that escaped from its cage at an upstate New York zoo and bit a zookeeper has been captured in a zookeepers' lounge and has been tranquillised. The Buffalo Zoo says a 24-year-old male gorilla named Koga got out of his cage into an aisle where the keeper was working on Monday morning and bit her on the hand and calf. The keeper locked herself in with the zoo's other gorillas and called the animal escape team. Police locked down the zoo while Koga was confined to a lounge outside public areas and was tranquillised. The Buffalo Zoo has six western lowland gorillas in its main animal building: Koga, four females and a baby female. It's investigating how Koga escaped. The zookeeper suffered minor bite wounds. She was taken to a hospital for evaluation.