Fire officials said the Hawk Fire remained completely uncontained as extreme fire behaviour and strong winds drove the flames through dry vegetation. Several structures have been destroyed in the blaze.

At least six people have been injured in the fire, including three civilians and three first responders. Officials said another 45,000 people were placed under an evacuation warning as the wildfire continued to spread.

About 10,000 customers were without electricity in Washoe County on Sunday as the wildfire threatened communities around Reno, the county's seat and most populous city.

Nevada Governor Joe Lombardo declared a state of emergency for Washoe County on Saturday night as officials worked to protect residents and deploy emergency resources.

Lombardo warned residents Sunday that the fire remained a rapidly evolving situation and urged people in affected areas to stay informed and follow directions from local authorities.

Earlier in July, another wildfire in Southern California, dubbed the Summit Fire, grew to nearly 2,700 acres (about 10.9 square kilometres), forcing evacuations amid a dangerous heat wave.

The Summit Fire was reported Friday afternoon in Llano, a small community near the Los Angeles and San Bernardino county line. California fire officials said the blaze remained uncontained as of Saturday morning.