Zoo keepers have launched an investigation to establish how five wolves escaped from their pen.
Three timber wolves were shot dead and two others recaptured after they escaped through a damaged fence at Colchester Zoo, Essex, yesterday morning.
One of the wolves which was shot was found beyond the zoo's perimeter after an eight-hour search.
Staff were said to be devastated by the deaths.
A zoo spokesman warned: "They are wild animals and in an unpredictable situation they would have posed a risk to the public."
Today zoo bosses said they were trying to establish how the damage was caused.
"Colchester Zoo management are holding an investigation today, and we have no further comment to make at this time," the spokesman added.
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