Strong winds and low humidity combined Thursday to create a worrisome risk for fire throughout the state, prompting Gov. Mark Dayton to activate the Minnesota National Guard to assist in suppressing wildfires.

Two Blackhawk helicopters equipped with 660-gallon water buckets will help local authorities and the state Department of Natural Resources (DNR) extinguish fires reported Thursday in the east-central part of the state.

At least a dozen farm animals were killed in a barn fire Thursday afternoon in Elk River, said fire chief John Cunningham. Calves, goats and smaller animals were trapped when a barn on the 22300 block of Jarvis Street became engulfed in a wind-fuled fire. No humans were injured.

It took firefighters about four hours to put out the blaze, partly due to the number of hay bales inside.

Small grass fires also ignited patches of dry land in Stearns and Ramsey counties, destroying several acres.

The National Weather Service (NWS) said there is a high fire danger stretching from the southwest corner of the state all the way to the Iron Range and the North Shore.

Sustained winds out of the west at speeds of up to 30 miles per hour — gusts even stronger — were merging with humidity readings as low as 15 to 20 percent, the weather service said.

"Any fires that develop will likely spread rapidly," the NWS said in its warning. "Outdoor burning is not recommended."

The DNR this week extended burn restrictions in parts of north-central and northeastern Minnesota, meaning that open burning of brush or yard waste is prohibited.

While the burning restrictions do not apply to campfires, the DNR urges campers to keep the area around a fire clear, monitor it closely and ensure that it's cold to the touch upon extinguishing.

Concerns over grass and forest fires were prompted by an early snow melt, which has exposed dead grass and brush that can light easily.

Debris burning is especially dangerous during April and May, when most wildfires occur in Minnesota, the DNR said.

The agency said it expects the restrictions to remain in place until the terrain greens up.

"Each year, we lose more outbuildings and homes to small 1- to 2-acre fires than to the big fires," said Ron Stoffel, DNR wildfire suppression supervisor.

"Even a small grass fire has the potential to injure people, and cause damage to property and resources," Stoffel said. "Last week, a small grass fire ended up destroying a homeowner's garage."

The state sees more wildfires in April than any other month, with an average of 775 that burn 19,669 acres.