Copenhagen Zoo says a man has jumped inside a polar bear's enclosure, forcing zookeepers to fire rubber bullets at the animal while he was rescued.

Zoo spokesman Jacob Munkholm Hoeck said Wednesday the man, who was not identified, was "pulled out and was able to walk" but was sent to the hospital in an ambulance.

Munkholm Hoeck says zookeepers fired several rounds of rubber bullets at the bear to get it to back off.

On Twitter, police described the man as "mentally unstable," adding that the polar bear had "walked on him" before he was rescued.

In July 2012, Siberian tigers fatally mauled a 21-year-old Afghan-born man inside an enclosure at the zoo.