London Zoo went into emergency lockdown for an hour after a “psycho” 29-stone gorilla who had been put on a diet escaped from its enclosure, forcing staff and visitors to shelter inside buildings.
People took refuge in cafes, the aquarium and butterfly enclosure as sirens went off and armed police arrived to help capture Kumbuka, a silverback western lowland gorilla.
Visitors reported the lead male in the gorilla enclosure had been visibly agitated before the incident and suggested that one of the animals had been throwing itself at safety glass.
Police said the animal was finally subdued and recovered after keepers fired a tranquilliser dart.
Kumbuka had been put on a diet recently, but a spokesman for the zoo said that he was given chocolate chip muffins – his favourite treat – when he regained consciousness after being tranquilised.
The zoo said he had only got into an enclosure that keepers can access and not into any public areas.
The spokesman said the incident was being investigated, but added: “At no time was there a risk to our visitors or the gorilla himself.
“Within a short time he was back in his den and this evening he was back with his family and grumbling away.”
One zoo employee told Buzzfeed News that the gorilla had smashed the enclosure glass several times. A staff member is said to have described it as a “****ing psycho”.
Oliver Barker, 24, who was visiting the zoo for a marketing conference, said the gorilla had seemed “agitated” earlier in the day, and keepers had warned visitors not to stare at him.
He said: “He looked like he was in a sort of trance, he definitely wasn’t relaxed at all.
“He looked very intimidating. The zookeeper came over and said, ‘don’t aggravate him by staring at him.”
“She could tell he was very agitated, and lo and behold soon after we were told he had escaped.’
One of Mr Barker’s colleagues later saw the animal charging at the enclosure glass.
“Five minutes after that we were told to get into the nearest safe room.”
Matt Hampson, who was due to give a talk at the zoo, said he heard a loud alarm going off.
“There were lots of keepers and people running about. We were told to go into a room because an animal had escaped. They didn’t say what it was.
“We were in there for about an hour and then one of the keeper’s came to the door and said you can’t do the talk because there’s a gorilla that’s escaped and that everybody had to leave the premises.
“There were people rushing around looking quite concerned really. It was scary. I did actually have some bananas in my bag so I made light of it and asked if he wanted to eats some of them.
“We were obviously having a laugh and a joke about it but you don’t actually expect this… it’s quite worrying, really.”
Jonny Briers, 22, told the Evening Standard: “We were at the gorilla enclosure and the gorilla charged at the glass. It didn’t break it, we saw it do it earlier in the day as well.
“And then we started to leave and we heard the siren go off. Then we saw zookeepers running and they told us to go inside. We went into the aquarium and they locked the doors.”
Visitors posted pictures of people sheltering inside cafes and the butterfly enclosure and armed police could be seen outside.
Neuropsychologist Dr Jonathan Mall was a research conference at the zoo when the incident happened.
The 33-year-old, from Hamburg in Germany, said he saw two members of staff “frantically running around” in the enclosure, and when he jokingly asked one if a gorilla was loose they said: “I don’t know, please go outside the area.”
He added: “Another distressed staff member said ‘Please move quickly and go inside a building’, and she told us to leave, I saw other people running for buildings.”
Scotland Yard said officers had attended in support of zoo staff, but had not subdued the animal.
The £5 million Gorilla Kingdom was opened by the Duke of Edinburgh in 2007, then the largest investment at the zoo for 40 years.
Kumbuka is one of at least six gorillas at the zoo. He arrived from Paignton Zoo in Devon in early 2013, and according to the zoo’s website “despite never having had a female mate before,was quickly spotted flirting with females Mjukuu and Effie”.
The zoo will be open again on Friday..