Unusually dry trees and vegetation are fueling a raging wildfire near Las Vegas that has prompted evacuations of more than 500 people and left a thick blanket of smoke over the city, officials said.

The lightning-caused fire on Mount Charleston has grown to nearly 11,000 acres, or 17 square miles, U.S. Forest Service spokeswoman Julie Thomas said, and there has been no containment of it so far.

No injuries or damage to structures were reported.

The Clark County Department of Air Quality extended a health advisory for smoke and ground-level ozone due to the fire through Sunday around Las Vegas.

Doug Martz, 70, was among those forced to flee homes as 200-foot-high flames approached. He said he wasn’t alarmed that his home might be destroyed.

“Such is life. Pretend you just got to go to (Los Angeles) for a couple of days,” he told the Las Vegas Sun at a Red Cross evacuation center Friday night.

Forest Service officials said they found extremely brittle needles and leaves on ponderosa pines and mountain mahogany with no moisture whatsoever in the fire area, located 25 miles northwest of Las Vegas.

More than 400 firefighters were battling the blaze with the help of an aerial assault involving five helicopters and five air tankers. A Type 1 team with more extensive training and access to resources assumed command of the blaze.

The National Weather Service was calling for a chance of afternoon thunderstorms through Sunday around Mount Charleston, with highs in the low 80s and winds of up to 20 mph.

The Clark County Department of Air Quality extended a health advisory for smoke and ground-level ozone due to the fire through Sunday around Las Vegas.

Over 100 people, including people who evacuated their homes, attended a meeting Friday night in Pahrump where fire officials answered residents’ questions. Officials pledged continued efforts to protect homes and sensitive wildlife species.

Firefighter Troy Thomas said Sunday’s deaths of 19 firefighters in Arizona prompted him to be more aware of his surroundings. His firefighting team from the northern Nevada community of Owyhee traveled to the fire in a truck with the heater turned on to adapt to the heat in southern Nevada.

The fire began Thursday after a dry winter and amid a record heat wave that saw temperatures reach up to 117 degrees in Las Vegas.

To the north, crews were hampered by sustained winds and low humidity as they fought a wildfire that had grown to over 7,000 acres, or 11 square miles, in the Pine Nut Mountains near Gardnerville, 60 miles south of Reno. The blaze was only 20 percent contained Saturday.

No injuries or damage to structures were reported, but residents of about 20 homes remained under a voluntary evacuation notice.

Over 300 firefighters were battling the blaze, which posed a severe threat to critical sage-grouse habitat. Officials are working across the West to keep the chicken-sized bird off the federal list of threatened and endangered species.