Conservation officer Joe Caravetta said the men were near the top of Mount Proctor when the bear attacked.
He said one man hit the bear with bear spray, but that didn't stop the animal.
"That individual had a shotgun with him and at that time shot at the bear, hitting the bear," Caravetta said.
"But the bear still continued to pursue that individual and knock them down and chewed on him a bit before proceeding with its cub."
The men suffered injuries to their arms and legs but were able to flee and make their way to a nearby hospital. Caravetta said one man has been taken to a hospital in Lethbridge for treatment, while the other was treated at a hospital in Fernie and has since been released.
Conservation officers are investigating and attempting to locate the grizzly bear.
The Fairy Creek Proctor Mountain Bike and Hiking trail remains closed until the bear is found.
"It's very thick dense bush and we are asking the public to stay out of there," Caravetta said. "These gentlemen did nothing wrong, nor did the bear — it was just wrong place, wrong time."