The independent police investigation agency, the Bureau des enquetes independantes, says it has been told that Mounties responded to a report of a disturbed person in the Miramichi area on Friday night.
It says preliminary information indicates RCMP officers found the man armed with a knife in a building and used an electronic stun gun on him several times without success.
Investigators say the man was allegedly shot when he charged police, was given first aid, and transported to hospital where he was declared dead.
It says eight people have been assigned to determine what happened.
New Brunswick RCMP were not immediately available for comment.
This is the second fatal police-involved shooting in New Brunswick this month.
On June 4, Chantel Moore, 26, died after being shot by an Edmundston Police Department officer.
Moore, from a First Nation in British Columbia, had moved to the community to be near her mother and 6-year-old daughter.