RENO, Nev. (AP) -- Smoke from a wildfire that has closed a 25-mile stretch of Interstate 80 near the Nevada-California line has triggered an air quality warning in the Reno-Sparks area.

The Washoe County Health District said Tuesday that young children, the elderly and people with lung disease or asthma should avoid any extended outdoor activity.

The Sierra Front Interagency Fire Center says no evacuations have been ordered but seven structures currently are threatened and fire crews in the Reno-area remain on alert in case the winds push the flames toward the city.

Truckee Meadows Fire Protection Chief Charles Moore says it's "an unpredictable situation."

Trucks have lined up for 3 miles along the shoulder of westbound I-80 where the interstate is closed at the California-Nevada line. Authorities say they have no idea when the highway will reopen