Officials say two National Guard helicopters joined other aircraft Sunday in dropping water on the blaze near the towns of Bastrop and Smithville.
Gov. Rick Perry has activated state resources, including four Blackhawk helicopters equipped to drop water and fire retardant, firefighters and equipment.
The wildfire has charred just over a square mile since it was started Saturday by a fallen power line.
Texas Forest Service spokesman Lewis Kearney says the fire is about 70 percent contained and that no additional structures are threatened.
Residents who were evacuated during the night were being escorted back into the area Sunday to identify their property.
Bastrop is about 30 miles southeast of Austin.