Raging rivers swollen by more than 40 inches of rain swept away houses and forced thousands of people to higher ground last night as flooding inundated much of southern and central Texas.
The National Weather Service warned of "catastrophic flooding" and urged those downstream to get out of harm's way.
The rain, which began pounding the region a week ago and has reached 42 inches in places, has been blamed for seven deaths.
Hundreds of homes have been damaged or destroyed by normally placid rivers turned into dangerous torrents sweeping down the limestone canyons of the Texas Hill Country.
Towns along the Medina River west of San Antonio and the Guadalupe River to the north and east were evacuated as the rivers rose near record levels.
"People need to get out of their homes if they live anywhere near the Guadalupe," County Sheriff Arnold Zwicke warned from his office in Seguin, 30 miles east of San Antonio.
Television reports showed a large house floating in rapidly running river near the town of New Braunfels, where an estimated 5,000 people fled the floods.