(RENO, Nev.) -- An out-of-control brush fire that ignited over the weekend in the hills in Northern Nevada near Reno has grown to more than 15,000 acres, prompting a massive evacuation of 42,000 people, authorities said on Monday.

A preliminary investigation has found that the Hawk Fire was human-caused, authorities said. They did not immediately release details on whether the blaze was intentionally or accidentally set.

"We do know it was human-caused because there were no natural ignition sources that were present in that area," Chief Richard Edwards of the Truckee Meadows Fire Protection District said at a news conference on Sunday.

About 90,000 people have been affected by the wildfire, including 42,000 who have been forced to evacuate their homes and another 45,000 people who have been warned to be prepared to evacuate, officials said.

About 14,000 homes are in the evacuation area and authorities confirmed that some residences have been destroyed.

The fire remained 0% contained after burning 15,051 acres, Nevada fire officials said in an update on Monday morning.

Officials reported some good news on Monday, saying firefighters made progress overnight in battling the blaze "despite extreme fire behavior observed during the incident."

"Hot, dry and breezy conditions are expected to continue supporting active fire behavior over the next 48 hours. The fire has the potential to spread northeast and northwest, and conditions remain dynamic and subject to rapid change," fire officials said in the update.

About 1,000 firefighters and other first responders are battling the fire from the ground and air, officials said.

At least three civilians and three first responders have been injured by the fire, officials said.

The number of homes destroyed or damaged remains unclear. Officials said unsafe conditions have prevented them from getting a clear damage assessment.

The fire was continuing to move in the direction of heavily populated urban areas, authorities said.

Nevada Gov. Joe Lombardo said in a statement over the weekend that the fire was "spreading quickly and threatening homes and structures" and that he had declared a state of emergency for Washoe County.

"The Hawk Fire is a very dynamic incident for us as it's being driven by the winds," said Truckee Meadows Fire Chief Richard Edwards in a video posted to social media. "The wind-driven fires move very rapidly into our residential areas, creating a lot of challenges for our firefighters to save homes and protect lives."

He urged residents to pay attention to evacuation orders, leave early if directed and have a travel bag ready.

Weather in the fire zone northwest of Reno is expected stay mild on Monday, with highs in the middle 80s, with gusts up to 25 mph, and relative humidity around 25%. 

On Tuesday, temperatures are expected to the upper 80s, with gusts between 25 and 30 mph.

The Washoe County School District announced that all classes, events and activities are canceled on Monday.

"The decision to close schools is due to evacuations, impacts on the regional public safety resources, and to help keep roads clear for emergency vehicle," the school district said in a statement.

Northwest Specialty Hospital in Reno announced Sunday that it was evacuating patients from the facility "out of an abundance of caution."

"Patients have been safely transported to appropriate locations where their care will continue without interruption – no patients or staff remain in the building," the statement said.

About 10,000 utility customers remained without power on Monday, down from about 60,000 at the peak of the blaze, officials said.

Northern Nevada Health Systems said it had temporarily closed the emergency room at North Valleys north of Reno due to evacuations.

"My heart goes out to anyone in our community who has been impacted by the dangerous and fast-moving Hawk Fire," Reno Mayor Hillary Shieve said in a statement on social media, urging residents to evacuate if told to do so and saying some structures had already burned.

The statement added: "Our firefighters and first responders are heroically fighting the fire and the high winds to save lives, homes, businesses, livestock and pets."

The Washoe County Sheriff's Office said it was monitoring the fire.

ABC News' Kyle Reiman contributed to this report.

Copyright © 2026, ABC Audio. All rights reserved.