TOWN OF GORDON, Wis. -

A wildfire that has burned more than 8,700 acres in northwestern Wisconsin started in area where workers were doing logging operations.

Wisconsin Department of Natural Resources spokesman Ed Culhane says officials are investigating whether a spark from a piece of logging equipment started the fire around 2:30 p.m. Tuesday in Douglas County.

Firefighters worked throughout the night to contain the smoky wildfire that has destroyed nearly 50 structures and forced dozens from their homes in Douglas and Bayfield counties. They had it about 90 percent contained Wednesday morning, meaning firefighters have stopped most of the fire from spreading.

Culhane said Wednesday morning it could still be days before they get the fire completely put out. No injuries have been reported.