DULUTH (AP) -- U.S. Forest Service officials have extended the closure of the Boundary Waters Canoe Area Wilderness as Minnesota's largest wildfire doubled in size.

The Greenwood fire burning in the Superior National Forest in northeastern Minnesota grew to about 30 square miles Monday, and four new smaller fires started within the BWCA.

Officials have decided to keep the popular wilderness closed for another week, until Sept. 3, dealing a blow to tourists who spent months planning their trips there as well as to the outfitters and other businesses that depend on them.

There are 13 fires burning in the forest, although not all are being actively fought and some have been contained.