Fire officials say a group of six fires burning in Montana has blackened more than 270 square miles amid hot, windy conditions.

The group of blazes, known as the Rosebud Complex, grew Monday by about 10 square miles in an area south of Rosebud. Lightning sparked the fires last week.

Nearly 900 firefighters are at the blazes, which is about 30 percent contained.

The National Weather Service has issued a red flag warning for the region as temperatures rose to the mid-90s and winds buffeted southeast Montana.

Gov. Brian Schweitzer declared an emergency on Monday across roughly half the state as wildfires scorched almost 430 square miles in the past week. The order paved the way for mobilization of the Montana National Guard and other resources to help.