LONDON — A silverback gorilla escaped from an enclosure at London Zoo Thursday, sparking a frantic search by keepers and armed police. Some visitors were locked down in a cafeteria until the animal was sedated and recaptured.

The male gorilla, Kumbuka, was subdued by a tranquilizer gun and recaptured within an hour, zoo officials said.

Malcolm Fitzpatrick, the zoo’s curator of mammals, said there were no injuries to visitors or zoo workers, adding that Kumbuka recovered quickly.

“I’m happy to report he’s actually up and grumbling and interacting with the rest of his gorilla family,” Fitzpatrick said.

He said Kumbuka got out of a back den into a secure keeper area, but never made it into the parts of the zoo where about 100 visitors remained near closing time late Thursday afternoon.

The gorilla’s escape is being investigated by zoo officials. There were eyewitness reports indicating he was agitated before he escaped from the zoo’s Gorilla Kingdom attraction.

The zoo, inside Regent’s Park in a crowded London neighborhood, houses at least seven gorillas. Its website describes Kumbuka as a western loawland gorilla who has fathered two children since 2014.

Eyewitnesses said Kumbuka banged on the walls of his enclosure before he got out.

Jonny Briers, 22, told the Evening Standard newspaper he observed the gorilla charging at the glass at the end of its enclosure, but that the glass didn’t break.

Briers said he heard a siren go off shortly afterward and saw zookeepers running from the scene and telling visitors to get inside.

“We went into the aquarium, and they locked the doors,” he said.

Witness Brad Evans told BBC Radio that he was drinking coffee in the zoo cafeteria when zoo workers told visitors they were locked in and couldn’t leave because a gorilla had gotten out of its enclosure.

He said armed police quickly arrived and that customers were allowed to leave the zoo shortly later.

In May, a gorilla was shot dead at the Cincinnati Zoo after it grabbed a 4-year-old boy who had fallen into a moat.

In 2007, a 400-pound gorilla escaped from an enclosure and ran amok at a Rotterdam zoo in the Netherlands, biting one woman and dragging her around before he was finally subdued.

The Diergaarde Blijdorp zoo was evacuated and the 11-year-old gorilla, named Bokito, was eventually contained in a restaurant within the park.