ROSEAU, Minn. (AP) - The state Department of Natural Resources unintentionally sparked a wildfire this spring in Roseau County that burned 4,500 acres.

Reports say an investigation shows the April Palsburg wildfire started in a slash pile.

Burning slash piles is a common for DNR forest management. Debris left by logging crews is pushed into piles and lit, making room for tree seedlings.

The DNR's Forestry Division Director, Forrest Boe, said DNR workers lit the pile on in November 2014. It appeared to have burned out, but coals buried in root clusters smoldered through the winter.

Boe said strong winds fanned those coals to flame on April 15. The fire was contained by the next morning. He says the fire might not have happened if there had been more snow.