WATFORD CITY (AP) - Officials of Theodore Roosevelt National Park say 667 acres were burned in the park's north unit late last week, under the watchful eye of firefighters.

The prescribed burn happened Thursday at the unit's northwest corner. McKenzie County residents could see white smoke in the distance.

The prescribed burns are expected to continue in the park through the end of the month.

Fire management officer Rod Skalsky says the burns help the park diversify its plants, and that leads to more diversity in animals and insects.

Park officials say the fires are carefully planned and they keep in close contact with the National Weather Service to check on any changes in temperatures or wind speed.