Federal, state and local fire crews fighting the fast-growing fires racing across northwest Minnesota may get some help from snow and rain Wednesday.

The wind-driven flames expanded exponentially Tuesday, with one fire ending the day eight times larger than it had been in the morning.

A blaze near Karlstad forced evacuations and destroyed six homes in the city, according to Jean Bergerson, spokeswoman for the Interagency Fire Center. Another, burning grassland, woods and peatbogs north of Red Lake, ran 6 miles beyond fire lines after firefighters were moved from that remote area to help protect Karlstad.

"We had to split the resources to see where they could do some good," Bergerson said. "That's where you get into problems in weather like this."

A third fire, in a peat swamp near Viking and believed to have been knocked out last weekend, revived and was burning a 5-mile corridor Tuesday afternoon.

A total of eight fires spread from nearly 3 1/2 square miles in the morning to more than 15 square miles by Tuesday evening as high winds, low humidities, and relatively warm temperatures inflamed a landscape already crisped by drought and the onset of fall.

Wednesday's forecasted rain-snow mix is not likely to extinguish them, but will help, Bergerson said. "The weather is going to change in our favor for a couple of days ... There's a good chance we're not going to get a lot of fire starts [Wednesday]. We're not going to be pulled in so many directions," she said.

The approaching cold front prompted the National Weather Service to lift the "red flag" fire warning that had been in place over the western half of the state for several days, and replace it with alerts for accumulating snow.

Portions of Karlstad, a city of 760 people, were evacuated Tuesday afternoon after a fire south of the city ran 3 miles in 20 minutes to the city's edge. Helicopters dumped fire retardant on the city.

"The whole town is just in smoke," said Karen Wikstrom, a waitress at the Nordhem Restaurant. "It's so bad. Helicopters are dropping stuff. We can hardly breathe."

Travel in and out of the city was restricted and many area highways were closed due to thick smoke and low visibility, but officials were restoring access Tuesday night.

Residents of a nursing home and assisted living center were moved first to a church and then to other care centers in surrounding communities, or picked up by family. Emily Straw, the center's director, said at one point in the afternoon she saw 8-foot-high walls of flame nearing the city. By evening, she said, the landscape on all sides of town was black. She said the center would remain closed at least through Wednesday.

About 130 firefighters were working on the eight different fires Tuesday. They will be joined by firefighters from Michigan on Wednesday, Bergerson said. At Hallock, about 30 miles northwest of Karlstad, a temperature of 73 degrees was accompanied by an extremely dry humidity and winds gusting to 43 miles per hour.

Gov. Mark Dayton authorized the use of four National Guard helicopters -- three Blackhawks and one Chinook -- to help fight the fires.

Fires had been flaring up across the region since last weekend. One fire destroyed an unoccupied farmhouse near the Canadian border Saturday. No injuries were reported.

Bill McAuliffe • 612-673-7646