At Loro Parque, a zoo and amusement park on the Spanish island of Tenerife, an employee wearing a gorilla costume was shot in the leg by a veterinarian who apparently thought the park employee was a real gorilla. According to Seattle PI, via a Google translation of the original article in La Opinión:
During a practice drill, the employee donned the costume and ran around the grounds to add realism to the event, but apparently the vet didn't know it was a drill and opened fire with his tranquilizer gun on the hapless employee—who apparently had an allergic reaction to the dose, designed to stop a 400 pound gorilla in its tracks.
Drills of this sort aren’t just monkey business. They’re a common occurrence at zoos around the world—see hilarious photos and video of zookeepers in Japan wrangling a guy in a (less realistic) gorilla suit earlier this year.