HEADLINE CORRECTED BASED ON NEW INFORMATION, SEE UPDATE BELOW:
A man dressed as a gorilla at a Tenerife, Spain zoo who was participating in a drill was mistakenly shot with a dart containing a massive dose of tranquilizer. Apparently, the vet who fired the shot wasn't aware that it was a drill. From the zoo's statement:
"Loro Parque simulated the escape of an animal from its enclosure in the gorilla park.
"As part of the simulation, which took place in the security zone of the area and was attended only by authorised personnel, they set off the emergency alarm.
"Once they had carried out the various procedures, one keeper in the wild mammals team was accidentally struck by the medical tranquiliser that vets use in these instances.
"As a result, emergency services were called and he was taken to hospital."
"Zoo employee shot in error while dressed as a gorilla" (Irish Examiner)
UPDATE: The Zoo tells the The Telegraph that the employee shot with the tranquilizer was not wearing a gorilla suit.