For humans, polar bears are perhaps the most dangerous of all ursines. That's why Churchill, Manitoba has a special-built jail for them and residents leave their car doors unlocked.
The Noregian archipelago of Svalbard, which is frozen year-round is home to many polar bears. As a result, carrying a rifle while outside of a settlement is not only lawful, but mandatory.
This gentleman in the village of Pyramiden was caught by surprise by a polar bear. He fired off a round from his rifle at the bear, which still charged him. The man fled on foot until he got onto a snowmobile. Nonetheless, the bear kept up the chase. It's not a bad strategy for a polar bear, as the species can run at up to 25 MPH.
-via kira