Terrified zoo visitors were faced with an angry grizzly bear smashing the glass of its zoo enclosure in front of their eyes.

The animal had been wrestling with other bears before it picked up a 50lb rock and started hitting the glass repeatedly.

Visitors at Minnesota Zoo were shocked as the glass shattered - but luckily remained in place.

Eyewitness Robin Ficker said the bears were “ wrestling with each other and looking at the people” before the incident.

He told the Minneapolis Star Tribune: “[The bear] picked up from the bottom of the pool a rock that had to weigh 50 pounds.

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“And while many people were standing there, he slammed it against the glass several times.”

Zoo animal collections manager Tony Fisher said that the glass stayed in place “like a windshield” and confirmed that no animals or people were hurt.

He added: “We’ll have to go back through the exhibit and anchor down anything they can lift.”

It’s thought that the bear responsible was an adult male, that can weigh up to 900lbs.

Pictures courtesy of Twitter/MattMcNeilAM950