Zookeepers at a zoo in Ueno, Tokyo, held an emergency drill with one of their own keepers dressed in a gorilla costume.
Stunned onlookers, including a bewildered elephant, watched as the 'gorilla' was tranquillised, caught in a net, and then bundled into a back of van.
But all's well that ends well for the 'gorilla' as he was happy to pose for pictures at the end of the drill.
He was then released and went back to work at the zoo...