Story highlights "He hit the window five times," witness says

Zoo says visitors were not in any danger

(CNN) The award-winning "Russia's Grizzly Coast" exhibit at the Minnesota Zoo attracts people in part because of the close proximity of bears to guests while still remaining in a simulated natural habitat.

But zoogoers in Apple Valley were not anticipating the brown bears, sometimes called grizzlies, to get any closer than that, until one of the three bears in the exhibit Monday shattered part of the multi-pane viewing glass with a rock. The glass remained in place.

"The noise of the rock into the glass was so loud that it reverberated, and that is when people ran," said Robin Ficker, a lawyer on vacation from Maryland who decided to stay to see what happened next.

"He was using a rock as a tool. ... He hit the window five times," he said.

"The exhibit was unique in the sense that the pond came right up to you, allowing you to be within inches of bears," said Ficker, who captured the now-viral picture of the aftermath.

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