Access to Yellowknife's Old Town was briefly shut down late on Monday as RCMP carried out what they termed a "high-risk take down" in the area.
Little else about the incident has been made public. Nobody has been arrested or charged.
Police said roads had been closed because of the risk to public safety during the operation, adding they considered the matter "an isolated incident."
No further information about what took place has been made available, and nobody involved has been identified.
The investigation is ongoing.
Police said there was no link to a separate incident in Old Town on Saturday, July 13, during which RCMP attended the scene of a reported assault.
RCMP arrived at 6:30pm to find the suspect had fled, while police said the victim of the alleged attack had been transported south by medevac. Their injuries were said not to be life-threatening.
That incident is also being investigated.
In a public post to Facebook, shared more than 200 times, Yellowknife resident Cameron Wilson described an assault taking place near the Gallery of the Midnight Sun art and gift store on Franklin Avenue in Old Town.
Wilson gave a description of an assailant riding a bike – which police did not immediately corroborate – and urged fellow residents to help catch the perpetrator of what he termed a "completely unprovoked" attack.