Five layers of glass separate visitors from grizzly bears at the Minnesota Zoo in Apple Valley, Minnesota, but one of them shattered when a bear smashed it with a rock on July 6, ABC News reports.
“One of the bears had a rock about the size of a basketball and managed to break one of the windows,” Tony Fisher, the zoo’s director of animal collections, said.
“At no time was there any danger of the bears getting out since there were still four layers of glass,” he added, "but we’re not going to trust it."
Fisher said there’s no way to know which of the three bears broke the 2-and-a-half-inch-thick glass. However, he told the Star Tribune he suspects it was a nearly full-grown male bear known as Kenai.
Kenai is “usually the clown out there, fooling around in the water,” Fisher said. “He didn’t know what he was doing. He was just being a bear.”
He told ABC News: “We thought we had all the rocks out of their exhibit, but one of them dug it up somewhere.”
Robin Ficker, a visitor from Maryland, told the Star Tribune he was watching “the bears wrestling with each other and looking at the people” shortly after the zoo opened.
Ficker said one of the bears “picked up from the bottom of the pool a rock that had to weigh 50 pounds. And while many people were standing there, he slammed it against the glass several times.”
The exhibit has been temporarily closed while the zoo waits for a custom-order piece of replacement glass, which is designed to absorb impact.