A gorilla that escaped its enclosure at London Zoo has been subdued by keepers using a tranquiliser dart and recaptured.

Staff at the zoo were forced to roam the premises armed with weapons as staff and visitors remained locked in for their own safety.

The incident has come just months after the gorilla Harambe was killed by staff at Cincinatti Zoo after it grabbed a child who had fallen into its enclosure.

Eyewitness Brad Evans told BBC Radio London: "We were having a cup of coffee in the main restaurant area when they locked us all in and said there was an incident.

"They gave us free teas and coffees and obviously we were asking what was going on and they told us that a gorilla had got out of its enclosure.

"As we were waiting we saw the police turning up in numbers with loads of guns."