PITTSBURGH, Nov. 6 (UPI) -- The mauling of a toddler by African painted dogs wasn't the first time the Pittsburgh Zoo had problems with that exhibit, officials said.
The zoo, which had been closed since Sunday's accident in which a 2-year-old boy fell into the enclosure and died, reopened Tuesday.
Zoo President Barbara Baker said it was not clear if the boy, Maddox Derkosh, died from the fall or from the dog attack that followed.
The dogs were under quarantine late Monday as the zoo opened an internal investigation. The quarantine was to last 30 days. There was no immediate word on the future of the exhibit.
The incident marks the first time a visitor has died at the Pittsburgh zoo in its 114-year history. A small memorial that included flowers, an angel figurine and a teddy bear was set up to remember the boy, KDKA-TV, Pittsburgh, reported.
"It's the worst nightmare as a zoo professional," Baker said.
The officials told KDKA nine of the dogs dug their way out of the main enclosure in May and ended up in a backup enclosure before they were corralled by zoo staffers.