London was thrown into a brief panic today after an adult silverback gorilla escaped from the city's zoo. On social media, people in London and beyond pleaded that the gorilla be spared, hoping to avoid a repeat of the controversial killing of the zoo gorilla Harambe in Cincinnati in May.

The 18-year-old gorilla Kumbuka somehow escaped from his den at the London Zoo around 5:13 p.m. local time Thursday, zoo spokesperson Nicola Kelly confirms. And although the zoo was quickly put on lockdown, Kumbuka stayed isolated from guests, in an internal area of the exhibit.

“Staff responded immediately,” Kelly says. The metro police were called and zoo vets worked to quickly subdue Kumbuka by tranquilizing him.

Gorillas are rarely aggressive to people.