Bear throws rock, shatters glass barrier at zoo in Minnesota

APPLE VALLEY, Minn. -- The Minnesota Zoo has closed its brown bears from public view after one of the grizzlies broke a glass barrier with a rock.

One of the five layers of glass broke on Monday, July 6th inside the grizzly bear exhibit at the zoo in Apple Valley, Minnesota.

“One of the bears had a rock about the size of a basketball and managed to break one of the windows,” the zoo’s director of animal collections Tony Fisher told ABC News. "At no time was there any danger of the bears getting out since there were still four layers of glass, but we’re not going to trust it."

Officials said there’s no way to know which bear broke the barrier.

The glass is similar to a car windshield and is designed to absorb impact.