The American Fire grew to 1,750 acres overnight.

It continues to burn in a rugged area near Foresthill in the Tahoe National Forest. However, that town is not threatened.

A smoky sunrise near Auburn on Aug. 13. Photo/CalFire

Heavy smoke from the wildfire is expected to continue to fill the skies of Truckee, Reno and other areas. On Monday, Placer County issued an advisory about the bad air quality.

The fire is moving up and down the North Fork of the Middle Fork of the American River. While the fire is not affecting recreation on the river, people are advised to stay out of the area.

The cause of the fire, which started Aug. 10, is unknown.

— Lake Tahoe News staff report