Texas Forest Service spokeswoman Jan Amen said Monday that firefighters have been unable to begin containing the blaze. The forest service says the fire has destroyed as many as 300 homes scorched more than 17,500 acres (7,000 hectares).
The fire is roughly 30 miles (50 kilometers) from Austin and is moving away from the city.
KVUE-TV in Austin reports that nearly half of the 6,000-acre Bastrop State Park has burned.
It is one of several wildfires crews are battling throughout the drought-stricken state. A fast-moving East Texas blaze that killed a woman and her 18-month-daughter in the community of Gladewater on Sunday has been extinguished.