BOISE, Idaho -

More than 300 personnel have been called in to suppress a wildfire that is steadily spreading inside the Boise National Forest and that tripled in size overnight.

Fire officials say the lightning-caused Whiskey Complex Fire has consumed 7 square miles of forest land. Residents of 70 homes in the Garden Valley and Pioneerville area are on alert for a possible evacuation order.

Boise National Forest spokesman David Olsen says heavy smoke trapped by the area's inversion prevented firefighters from being able to use helicopters to put out the flames Thursday morning.

Due to high temperatures and extremely dry fuels, the fire isn't expected to be contained until the end of July.