Kumbuka, a male silverback, sparked an armed police response after his break out bid on 13 October The silverback gorilla whose escape sent ZSL London Zoo into lockdown made an "opportunistic" exit through two unlocked doors into a corridor where a keeper was working, the zoo said. Professor David Field, the ZSL's zoological director, said Kumbuka was kept calm by the member of staff, with whom he had a "close bond".