Northland Utilities is warning it may have to begin rotating power outages in Yellowknife Tuesday after a military helicopter struck a power line near Yellowknife Monday night.

The power distribution company has asked commercial customers with back-up generators to run them for the day.

A Canadian Forces Griffon helicopter struck the wire on its way to the Yellowknife airport at around 7:50 p.m. MT. The power went out in much of the city at the same time, and the outage lasted over an hour.

The helicopter landed safely and no injuries were reported. There were three people on board.

The aircraft, however, sustained "significant damage" according to a Canadian Forces spokesperson.

Robert Schmidt, director of hydro operations with the NWT Power Corporation, says the helicopter struck a power transmission line from the Snare Lake hydro plant. Power was restored using the diesel plants at Jackfish Lake and Frank's Channel and hydro power from Bluefish Lake.

He said they won't be able to assess the damage until crews can be dispatched to the location by helicopter.

The Griffon helicopter was returning to the Yellowknife airport after conducting air operations in support of Exercise Arctic Ram. It is from 408 Tactical Helicopter Detachment and is normally stationed at CFB Edmonton.