A hunter is facing life-threatening injuries after he was attacked by a grizzly bear in northern Alberta.

The Shock Trauma Air Rescue Service, or STARS, says the 48-year-old man was attacked Tuesday while hunting in the Swan Hills region north of Edmonton.

Cam Heke, a spokesman for STARS, says the big predator attacked the man from behind.

Heke says the hunter was able to scare off the bear by firing a shot from his gun.

He then managed to walk about six kilometres to an area where he could call for help on his cellphone.

The man was located and taken to hospital in Grande Prairie, where a trauma team was waiting for him. (CHED)