HELSINKI — Sweden is fighting its most serious wildfires in decades — including blazes above the Arctic Circle — prompting the government to seek help from the military, hundreds of volunteers and other European nations.

As of Friday, over 50 blazes were torching forests, mostly in central and western Sweden but also in the north, above the Arctic Circle, and on the Baltic Sea island of Gotland.

No deaths or injuries have been reported so far but large evacuations have taken place and thousands of people have been warned to remain inside with the windows shut to avoid breathing the smoky air. Finland and Norway have also reported wildfires in the past few days.

Some 500 voluntary soldiers from the Swedish military have been dispatched to help with Black Hawk helicopters in the central region of Alvdalen.

In some areas emergency rescue services have called for all able-bodied men to help out putting the wildfires that have raged this week.

"This is a serious situation and the risk for forest fires is extremely high in the whole country," said Jakob Wernerman, operative head of the Swedish Civil Contingencies Agency that is coordinating firefighting efforts.

The fires have come as Europe's Nordic region has experienced an intense heat wave in the past week. Temperatures have reached over 32 degrees Celsius (90 Fahrenheit) throughout Finland, Norway and Sweden. The weather also has been dry with no substantial rain for weeks — making the region's brush and forests highly flammable.

Swedish Prime Minister Stefan Lofven said Friday that his government is working "every minute" to get necessary resources to the hundreds of firefighters and emergency workers.

Sweden has received assistance — including water-bombing planes, helicopters and staff — from Italy, France and Norway. Denmark, Germany and Lithuania have also pledged to help.

France on Thursday delivered two Canadair CL-415 water-bombing planes, which can carry 6,000 liters (1,585 gallons) of water at a time. Italy dispatched similar planes to Sweden earlier this week.

Swedish media have shown dramatic footage of blazing forests, helicopters dropping water and firefighters trying to put out flames.

The Aftonbladet tabloid has run a special section titled "Sweden is burning!" that just covers news on the blazes. In an interview, water-carrying helicopter pilot Bjorn Franzen noted the difficulty of the mission.

"We fly mostly in low altitude. It's often difficult to see anything from the smoke," he told Aftonbladet. "It can be extremely difficult to see where our input is needed. Sometimes the wind changes direction and then we need to resort to different tactics."