Originally published August 16, 2013 at 10:11 p.m., updated August 17, 2013 at 8:58 a.m.
SACRAMENTO, Calif. (AP) -- The U.S. Forest Service has ordered an emergency closure for portions of the Tahoe National Forest near a remote Northern California wildfire that has burned more than 19 square miles of steep, wooded terrain.
The blaze, dubbed the American Fire, grew four square miles overnight. At the same time, firefighters made advances, increasing their containment of the fire from 37 percent Friday night to 45 percent Saturday morning, said Dana Walsh, a Forest Service information officer.
Heavy smoke from the fire 10 miles northeast of Foresthill at times has blanketed portions of the Sierra Nevada foothills, the Sacramento Valley and stretched to Lake Tahoe.
An air quality warning has been issued for Placer County, northeast of Sacramento. The Forest Service says smoky conditions might last through the weekend.
The fire is burning along a tributary of the American River. It's not threatening homes.
The closure order announced Friday includes a segment of the Western States Trail, which is used for endurance races between Auburn and Lake Tahoe.