A brown bear at the Minnesota Zoo smashed a large rock against the glass in its enclosure, shattering the glass Monday.

The bear, which is one of three in the Apple Valley zoo's Russia's Grizzly Coast exhibit, repeatedly slammed the basketball-sized rock against the pane, shattering it as zoogoers stood on the other side, the Star Tribune reports.

The incident happened around 9:30 a.m. Monday, Kelly Lessard of the Minnesota Zoo told BringMeTheNews, adding: "The bears immediately went back into their exhibit so there was never a safety threat to guests or the bears."

https://www.facebook.com/photo.php?fbid=10154017436084128&set=a.10150331185854128.420902.526659127&type=1

Zoo officials aren't sure which of the three bears broke the glass, but Lessard says it was likely Kenai, because he hangs around the front pool near the glass most often, but could have also been Haines.

The zoo exhibit is temporarily closed and will reopen once the glass is fixed. Lessard says there is no timeline for this as of now.

Rocks and other items the bears can lift up are supposed to be secured in place, a zoo official told the Star Tribune. The zoo plans to go through the exhibit and make sure everything else is anchored down correctly.

Similar incidents have happened at other zoos around the world, but Lessard isn't sure if this has happened at the Minnesota Zoo.

In 2012, a polar bear at a zoo in Europe threw a rock underwater, shattering the glass in its enclosure. In April, a gorilla charged at the glass at a Nebraska zoo, breaking it.