Republican governor Greg Abbott proclaimed 60 counties were in a state of disaster and called for extra emergency services to support local firefighters in tackling the blazes.

The unbridled Smokehouse Creek Fire, the largest of all the blazes, burned nearly 400 square miles - more than twice its size since it sparked on Monday, according to the Texas A&M Forest Service. It also forced major roads to close.

Unseasonable hot and dry conditions, along with strong winds, have caused the fires to ignite and spread across the state's grassy plains at an alarming pace - but authorities have not yet pinpointed the source of the blaze.

Pantex nuclear facility paused operations until further notice due to an out-of-control fire approaching its Panhandle site near Amarillo.

Its 16,000-acre site is home to the plant that builds and disassembles America's nuclear weapons.

"The fire near Pantex is not contained," the company said. "Response efforts have shifted to evacuations."

Pantex confirmed there was no fire on the site as emergency services continued to monitor the situation.

It added "all employees" had been accounted for and "non-essential personnel" were no longer on site.

Several fires in the Texan counties of Hemphill and Hutchinson were nearing the Oklahoma border, where some evacuations have also been ordered.

Hemphill County Sheriff Office urged anyone who remained in Canadian, about 100 miles northeast of Amarillo, to shelter in place or at the school gym because roads were closed.

Officials in Hutchinson County described the struggle of responding to the multiple fires in the area while juggling how best to inform civilians of what to do in a Facebook post.

"We have areas without power, water, and active burning," it said.

"Pray for the safety of all involved. And pack your go bag just in case. That is the best information we know how to provide right now."

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Posting on X, Texas senator Ted Cruz gave details of several shelters available for those impacted by the blazes which included a youth centre and churches.

Officials in the city of Pampa, about 40 miles southwest of Canadian, suggested residents evacuate to the south by bus.

One resident described the fire as a "monster", adding homes had been lost, along with livestock that could not be evacuated in time.