Smokehouse Creek Fire in Texas Grows to 500,000 Acres

Wildfires were spreading rapidly in Texas and Oklahoma early Wednesday, prompting evacuations and the closure of a plant that disassembles nuclear weapons.

In Texas, Gov. Greg Abbott issued a disaster declaration on Tuesday for 60 counties, activating state resources to help local firefighters and urged residents to limit activities that could create sparks.

The largest current blaze in the Texas Panhandle is the Smokehouse Creek fire. Early on Wednesday, it had spread quickly to at least 500,000 acres since igniting on Monday, fueled by strong winds and dry conditions, and was uncontrolled, according to the Texas A&M Forest Service.

That makes it the second largest in the state’s recorded history of wildfires, said Erin O’Connor, a spokeswoman for the forest service, on Wednesday. The largest was the Amarillo Complex, which scorched about 1 million acres in 2006.

“It is a significant fire,” she said. “It looks alarming how quickly it is spreading.”

She said the fire was fueled by dry, dead grasses in a drainage area, the “perfect environment to support the growth that we have seen.”

The fires raged and erratically shifted as colder air with a rapid change in wind direction pushed through the region on Tuesday. But the fire danger could ease on Wednesday and Thursday, as lighter winds are forecast across the Texas Panhandle.

“Conditions are going to moderate a little bit,” Ms. O’Connor said, adding that would give firefighters a window of opportunity to suppress the blazes before windy conditions pick up again on Friday.

Humidity is expected to drop again and strong winds are forecast to return on Friday.

Mandatory evacuations were ordered for several towns in Texas, the Forest Service said. The National Weather Service office in Amarillo, Texas, said that a neighborhood in that city had also been ordered to evacuate.

A hospital system in Canadian, Texas, evacuated all of its patients and staff Tuesday afternoon, according to the Hemphill County Hospital District. In Fritch, Texas, the Moore County Sheriff’s Office told residents of several neighborhoods to evacuate.

In Oklahoma, local officials told some residents of Ellis and Roger Mills counties, near the state’s western border with Texas, to leave.

Near Amarillo, a wildfire was burning north of Pantex, a plant that disassembles nuclear weapons, officials said. The plant paused operations and ordered nonessential personnel to evacuate.

“They are working hand in hand with the local jurisdiction and taken precautions to ensure their plant is safe,” said Ms. O’Connor, the forest service spokeswoman.

There was no fire on the plant’s site or near its boundaries, but nuclear safety officials were responding, said Laef Pendergraft, a nuclear safety engineer for the National Nuclear Security Administration production office at Pantex. The plant has an on-site fire department, he said, speaking at a news conference.

Unseasonably high temperatures and high winds were also spurring wildfires elsewhere in the Great Plains, including in Nebraska and Kansas.

Christine Hauser and Judson Jones contributed reporting.