A fire burning in the Sierra Nevada foothills toward Reno had grown to more than 10,500 acres, about 4,450 hectares, by Sunday, with 42,000 residents under evacuation orders and a further 45,000 in an evacuation warning zone, according to Al Jazeera. At least six people have been injured. No deaths have been reported.

The blaze, named the Hawk Fire after Hawk Meadow Trail where it began, started on Saturday. Nearly 10,000 homes and businesses had lost power by Sunday.

Wind is doing the work

Richard Edwards, chief of Truckee Meadows Fire and Rescue, described the problem in one sentence: "The Hawk Fire is a very dynamic incident for us, as it's being driven by the winds." His service attributed the fire's growth to strong, gusty winds, low humidity and dry vegetation.

That combination is the reason a fire of this size can be a genuine emergency for a city rather than a rural problem. Wind decides where the fire goes, and it can change the answer faster than crews can reposition. About 400 personnel were working the incident.

The evacuation argument

Reno's mayor, Hillary Schieve, made an unusually direct appeal to people weighing whether to stay. "If you have been told to evacuate, please don't wait!" she said. "Structures have already been burned in this fire, and your life is more important than a building."

She added a second argument that is often left unsaid: "Evacuating before the fire arrives also allows our firefighters to focus their efforts on battling the blaze." People who stay become people who may need rescuing, and rescue takes crews off the fire line.

Not everyone treats it as a crisis. Ted Melden, a retired police officer and firefighter, struck a more phlegmatic note: "I'm hoping they'll get a good handle on it. You just have to roll with the flow and be ready. Always be prepared and have a full tank of gas." Tyler Duvall, a local resident, put the cause simply: "The wind really blew it up."

The official response

Nevada's governor, Joe Lombardo, declared a state of emergency and mobilized the Nevada National Guard, including helicopter crews and 60 troops. An emergency declaration is largely a funding and coordination instrument: it unlocks state resources and clears the way for federal assistance.

Washoe County Sheriff Darin Balaam said an initial investigation had determined the fire was human-caused. That term covers a wide range, from arson to a spark from equipment, and the source does not say which is suspected here.

What we could not establish

We could not establish a containment percentage, a count of structures destroyed, or the severity of the six injuries. We could not establish how the fire was started beyond the sheriff's finding that a person, rather than lightning, was responsible. We verified this account from a single publication.