A series of wildfires swept across the Texas Panhandle early Wednesday, prompting evacuations, cutting off power to thousands, and forcing the brief shutdown of a nuclear weapons facility as strong winds, dry grass and unseasonably warm temperatures fed the blazes.

An unknown number of homes and other structures in Hutchinson County were damaged or destroyed, local emergency officials said. The main facility that disassembles America’s nuclear arsenal paused operations Tuesday night but said it was open for normal work on Wednesday.

Republican Gov. Greg Abbott issued a disaster declaration for 60 counties as the largest blaze, the Smokehouse Creek Fire, burned nearly 470 square miles (1,200 square kilometers), according to the Texas A&M Forest Service. That is more than twice its size since the fire sparked Monday.

Authorities have not said what might have caused the blaze, which tore through sparsely populated counties surrounded by rolling plains.

The weather forecast provided some hope for firefighters — cooler temperatures, less wind and possibly rain on Thursday. But for now, the situation was dire in some areas.

“Texans are urged to limit activities that could create sparks and take precautions to keep their loved ones safe,” Abbott said.

The Pantex plant, northeast of Amarillo, evacuated non-essential staff from the site on Tuesday night out of an “abundance of caution,” Laef Pendergraft, a spokesperson for National Nuclear Security Administration’s Production Office at Pantex, said during a news conference, adding that firefighters remained in case of an emergency.

The plant, long the main U.S. site for both assembling and disassembling atomic bombs, completed its last new bomb in 1991 and has dismantled thousands since.

Early Wednesday, Pantex tweeted that the facility “is open for normal day shift operations” and that all personnel were to report for duty according to their assigned schedule.

In Borger, a community of about 13,000 north of Pantex, Hutchinson County emergency management services personnel planned a convoy to take evacuees from one shelter to another ahead of expected power outages and overnight temperatures well below freezing.

As the evacuation orders mounted, county and city officials live-streamed on Facebook and tried to answer questions from panicked residents. Officials implored them to turn on their cellphones’ emergency alerts and be ready to evacuate immediately. They described some roads as having fire on both sides and said resources were being stretched to their limit.

People posted in the Facebook chat about their streets and communities, hoping for good news but more often the answer was either that an area had suffered damage or there wasn’t any indication yet of how it had fared.

Texas state Sen. Kevin Sparks said an evacuation order was issued for Canadian, a town of about 2,000 about 100 miles (160 kilometers) northeast of Amarillo. Later Tuesday, the Hemphill County Sheriff’s Office urged anyone who remained in Canadian to shelter in place or at the high school gym because roads were closed.

Evacuations were also ordered in several other towns in a swath northeast of Amarillo. Fire officials across the border in the area of Durham, Oklahoma, also encouraged people to evacuate.

At least some residents in the small city of Fritch in Hutchinson County were also told to leave their homes Tuesday afternoon because of another fire that had jumped a highway.

“Everything south of Highway 146 in Fritch evacuate now!” city officials said on Facebook.

On Tuesday evening, the fires were 20 to 25 miles (32 to 40 kilometers) from Amarillo, and wind was blowing wildfire smoke into the city, which could affect people with respiratory issues, weather service officials said.

The National Weather Service issued red flag warnings and fire danger alerts for several other states through the midsection of the country, as high winds of over 40 mph (64 kph) combined with warm temperatures, low humidity and dry winter vegetation to make conditions ripe for wildfires.

In central Nebraska, a mower sparked a prairie fire that has burned a huge swath of grassland roughly the size of the state’s largest city of Omaha, state officials said Tuesday.

(AP)