Paignton Zoo had to be evacuated as two gibbons escaped from their enclosure just hours after the site re-opened to the public.
Paignton Zoo reopened on Wednesday 14 September after a two-week closure because of an outbreak of bird flu.
The attraction was forced into an 'amber' alert after the animals escaped.
A witness said: "When I was leaving, at about 1.40pm, there was one escaped gibbon so staff were preventing visitors from using one of the pathways.
"It was near the entrance/exit so they had to temporarily stop people coming in which was a shame on their first day back - I left via the staff exit.
"I gather it was a large gibbon. A staff member told me it wasn't dangerous so it was amber alert."
Another said: "We have all been evacuated now but there are zoo workers running around like crazy".
A spokesperson from Paignton Zoo said: "Two gibbons escaped from their enclosure at Paignton Zoo.
"As a precautionary measure zoo visitors were evacuated from the area in accordance with our well-rehearsed escaped animal procedure."
In an update issued on Thursday morning, the zoo said the gibbons escaped into trees next to their island home.
The spokesperson said "at no point" were the animals missing or unaccounted for as they had not strayed more than 50 metres from their home.
"Staff were quickly able to recapture one of the animals and the second was contained within a secure area by late afternoon," they added.
"Staff successfully moved the animal from this secure area back to its home this morning and we will be reopening soon."
The spokesperson told ITV News staff regularly carry out escape drills and follow "strict protocol" for dealing with such events. The circumstances of the escape remains under investigation.