The blazes were blamed for at least seven deaths, four of them in a crash on a smoke-shrouded highway over the weekend. Four more bodies were found Monday evening in a car that had crashed into a ravine, and authorities suspected those deaths were also caused by the wildfires.
About 1,900 people in seven counties were evacuated.
"This has been a very deadly wildfire season, but Texas communities have shown strength, and we're going to continue fighting these fires from the ground and from the air," said Rachael Novier, a spokeswoman for Gov. Rick Perry.
There was no immediate estimate of the number of homes damaged or destroyed. Firefighters used bulldozers to plow fire breaks in the parched earth, while air tankers dropped water on the flames.
Jennifer Orand fled her doublewide mobile home Sunday in the tiny Panhandle community of Texroy to stay with a nearby relative. When she returned Monday, there was nothing left.
"I just started crying," said Orand, 27, who shared the home with her husband. "You hear all the time that people think it will never happen to you. I never thought I'd say that myself."
Eleven fires burned across an estimated nearly 700,000 acres Monday, up from 663,000 over the weekend. State fire crews fought more than 160 blazes in one 24-hour period.
The size of the scorched area easily eclipsed the 455,000 acres that burned in December and January, when the governor declared a disaster.
The cause of the latest blazes was under investigation.
The previous fires were apparently sparked by people who burned trash, tossed cigarettes or illegally set off fireworks in the middle of one of the worst droughts in Texas in 50 years.
About 3.5 million acres — 2 percent of the state's land mass — have burned since Dec. 26.
A blaze near Borger covered 432,000 acres, a fire near Groom consumed 211,000 acres, and a fire south of Childress burned 20,000 acres. Authorities believed the fire near Borger was sparked by power lines feeding oil field equipment at a ranch.
One of the most intense fires burned Monday about 10 miles north of Pampa. Winds blew it toward the town of about 17,000 people, said Donny Hooper, a spokesman for Gray County Emergency Operations.
"We're not sure where it's going to lead tonight," said Ken Hall, the community's emergency management coordinator.
Orand's mobile home, just four months old, had been filled with new furniture and appliances. At the burned-out site Monday, a melted jar of coins still smoldered.
Orand said she had evacuated without her wedding ring: "I think it's melted. It's gone."
A set of cement steps were all that remained, but she vowed to rebuild. "I'm not leaving this place," she said. "A tornado could come, and I'd still move back here."
Four people were killed Sunday in a chain-reaction accident involving nine vehicles on a smoky Interstate 40 near Groom, about 40 miles east of Amarillo. Three people died in fires near Borger — two of them trying to escape a grass fire that consumed their home, said fire Capt. Mike Galloway.
"The brush fire overtook their house and yard and got them," he said. "The flames just spread so fast."
Monday evening, four bodies were found in a car that had run off a road into a ravine in Roberts County.
Authorities said early evidence suggested the deaths were linked to the grass fires. No further details were immediately available; the investigation was continuing.
The fires were fanned by the same storm system that caused deadly tornadoes and storms in the Midwest. Winds of 55 mph combined with low humidity on Sunday to spread the flames.
The wind dropped to 15 or 20 mph Monday, and the humidity rose. But no rain is expected in the region before Saturday.