Heavy winds swept through parts of Texas and Oklahoma Wednesday, downing trees and power lines, causing flight cancellations and hindering efforts by firefighters to battle a brush fire.

Firefighters in Central Texas contained about 75 percent of a 1,200-acre brush fire Wednesday night despite heavy winds and extremely dry conditions earlier in the day, a Texas Forest Service spokeswoman said. They don't expect to have it completely contained until Thursday.

The fire had threatened about 150 homes near Driftwood, about 20 miles southwest of Austin, but no structures were damaged and no injuries were reported. Most residents told to evacuate Wednesday were allowed to return home later, forest service spokeswoman Traci Weaver said.

The cause of the fire wasn't immediately known.

In Austin, about 1,700 homes and businesses were without power Wednesday. Austin Energy officials said winds had damaged transformers and at least two power poles had been knocked down.

National Weather Service meteorologist Jason Dunn said winds would weaken substantially by Thursday, with a westerly breeze blowing 5-10 mph at the strongest. High wind warnings were to be in effect until about 6 p.m. for inland southeast Texas and midnight for the coast.

In Fort Worth, winds snapped a large branch that fell on a woman. She was listed in serious condition at the hospital.

Dallas-Fort Worth International Airport canceled 150 flights and delayed others. Delays ranged from half an hour to three hours depending on the destination, said airport spokesman David Magana. Winds also shut down two of five runways at Bush Intercontinental Airport.

Wind gusts up to 70 miles per hour in western Oklahoma also caused problems, toppling power lines Wednesday and overturning a tractor-trailer near Canute as a strong storm system pushed its way across the state.

Wind damage forced an elementary school in Moore, 10 miles south of Oklahoma City, to cancel classes Wednesday, and sporadic power outages were reported in several counties because of downed power lines, utility officials said.