"This was an incredibly sad incident and our staff are understandably heartbroken," zoo Director Derek Grove told the BBC. "Euthanasia is, and always will be, a last resort. Efforts to persuade Margaash to return to his enclosure failed and as the animal was close to surrounding woodland and dark was approaching, the vet did not believe a tranquilizer dart was a safe option due to the amount of time the drug takes to work.
"Safety of the public is always of paramount importance and our staff are highly experienced and rigorously trained."
Margaash was born at Banham Zoo in Norfolk in May 2010 and was transferred to the Dudley Zoo in September 2011, the Mail reported.