The Trailhead Fire has burned 2,161 acres, most of which are in El Dorado County. It remains at 12 percent containment.

Nearly 2,600 structures are still in the path of the blaze that started June 28. It is burning in the middle fork of the American River canyon.

The fire became more active Thursday as the inversion lifted in the early afternoon. According to CalFire, crews made good progress on the Placer County side, completing direct line across the west and northwestern edges of the fire.

Shelters have been set up in El Dorado and Placer counties for people who have been evacuated.

Smoke from the fire could continue to be a problem on Friday in the Truckee and Reno areas.

The cause is still under investigation.

— Lake Tahoe News staff report