SAN ANTONIO ? With heavy rain falling again, surging floodwaters ripped houses off their foundations Friday and pushed up against dams already straining to hold back swollen rivers across central and south Texas.

Hundreds of people fled their homes, joining more than 4,000 who have been forced out by high water in the past week. Flooding has killed at least seven people and caused tens of millions of dollars in damage.

A kyaker paddles past homes flooded by the Guadalupe River near Seguin, Tex. For days, deadly floodwaters have ravaged the Texas Hill Country and now communities downstream, such as Seguin, are feeling the pain. The Guadalupe River, which overflowed the spillway of an upstream dam, was coursing through nearby New Braunfels at about 70,000 cubic feet per second Friday; the normal rate is 300 cubic feet per second.

The extent of the damage is still being assessed.

The Medina River jumped its banks Friday near Bandera, a community battered by days of flooding. Judge Richard Evans said more than 100 houses and businesses had been damaged.

Floodwaters poured down a narrow canyon and into the small city of New Braunfels, 30 miles northeast of San Antonio. The murky, roiling water was filled with debris huge tree trunks, empty tires and inner tubes, even a six-foot propane tank dancing back and forth in the swirling current.

Sticking out of the water were the tops of homes. In some places, entire homes floated by stunned bystanders.

Standing under an umbrella, Dan Ackerman pointed to the spot where a house built on stilts had stood about an hour earlier. Now there was nothing but the river.

“It’s just gone,” Ackerman said. “It got washed away in 1998 and they rebuilt it. But it’s gone again.”

The Guadalupe River which overflowed the spillway of an upstream dam was coursing through New Braunfels at about 70,000 cubic feet per second Friday; the normal rate is 300 cubic feet per second.

Just northwest of San Antonio, a small dam burst and another one downstream on Chimney Creek was straining to hold back some 20 acres of water 30 feet deep.

Travis Lorton, a spokesman for the Helotes Fire Department, said officials were trying to get state and federal agencies to inspect the dam to determine its strength.

Hundreds of homes below the dam were evacuated as a precaution.

A region 100 miles by 150 miles has been swamped by rain for a week and 10 counties have been declared federal disaster areas. The National Weather Service said up to 4 inches of rain an hour was possible through the weekend in some places.

Thousands of residents of Castroville and LaCoste, west of San Antonio, were allowed to return to their homes Friday after being ordered out the night before. Medina County Sheriff Gilbert Rodriguez said they might have to leave again.

“We’re not out of the woods yet,” he said. “We thought we were, but not any more.”