RCMP said they received a call Wednesday night about the attack southwest of Norman Wells near the Yukon boundary.
Weather and darkness hampered search efforts until Thursday morning.
Cathy Menard, the chief coroner for the N.W.T., said the hunter was out with a guide when he was attacked.
"We understand the guide was the one who made the initial call for assistance."
Another coroner, along with a wildlife officer and Mounties, were investigating the scene throughout the day and were to return to Norman Wells with the guide later Thursday.
Menard said she doesn't believe the guide was injured.
She hasn't yet confirmed the hunter's identity and couldn't say where he is from.
Judy McLinton with the N.W.T. Department of Environment and Natural Resources said a wildlife incident response team was also to go to the site
"They'll be working with our partners on investigating the incident and they will begin a search for the grizzly bear."
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