He saw a man shoot into a bush, apparently with no idea what was in the bush. A wounded grizzly came out of the bush, and charged my roommate, who ran up a tree. He shot and killed the bear. I understand that the man who originally shot the bear went to jail and paid a fine. The black bear is sometimes brown, and is sometimes called a brown bear.
Grizzlies are often much larger than black bears, and have a hump on the back.