A jaguar that killed nine animals at a New Orleans zoo is believed to have bitten through steel mesh fencing that forms the roof of its enclosure.
Audubon Zoo's managing director Kyle Burks said the big cat managed to escape through the resulting small hole which was around eight by 10 inches.
Zoo officials are now looking for stronger materials to use instead of interlocking steel cables, Mr Burks told reporters.
Three-year-old male jaguar Valerio killed three foxes, five alpacas and an emu – but no humans were injured in the weekend incident.
The escape was discovered at 7.20am (1.20pm UK time) on Saturday when a member of staff delivering food in the swamp exhibit heard animals in distress.
Valerio was discovered in the fox exhibit and tranquilised before being safely taken back to his habitat in under an hour.
If the escape had occurred during the zoo's opening hours, staff would have implemented plans to usher visitors into secure buildings, Mr Burks said.
It was "conceivable" that the cat may have been able to eventually breach an outer perimeter and escape the zoo, he added.
"I can't necessarily say that there's no way he could have done that," Mr Burks said.
"Any time any of our dangerous animals are outside of their exhibit, we're going to take action. It doesn't matter where they are."
Audubon Zoo initially said they were "devastated" by the loss of six animals following the attacks, but that three injured animals were under professional care.
They later announced that one alpaca named Daisy did not survive and two foxes, Copper and Rusty, later died.
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Valerio was found to be in good health after an examination and will not be put down because he demonstrated normal predatory behaviour, officials said.
US Department of Agriculture officials have inspected the zoo since the escape and the Association of Zoos and Aquariums – the zoo's crediting organisation – has been notified of the incident.