The incident happened about 6 a.m. Wednesday at what's usually a small creek just outside Dublin, Texas, about 75 miles (120 kilometers) southwest of Fort Worth.
Crews launched a high-water rescue effort only to find the woman's husband clinging to a tree, Erath County Sheriff Matt Coates told the Stephenville Empire-Tribune . He was taken to a hospital. The mother's body was later recovered from the swamped car. Their 7-year-old son was found 400 yards (365 meters) further downstream, and their 3-year-old girl was found 3 miles (5 kilometers) downstream.
It was not clear immediately exactly how the accident happened, Coates said. An investigation is ongoing.
Damaging winds later Wednesday destroyed a warehouse near Bryan in Central Texas.
The National Weather Service reports about 3½ inches (76 millimeters) of rain had fallen overnight at the Stephenville Municipal Airport, about 26 miles (42 kilometers) northeast of the accident site.
Heavy rains moved across much of Texas and brought flash-flood warnings and high-water rescues. More rain was expected in North and Central Texas as a flash flood watch the National Weather Service had issued remained in effect.
Overnight torrents also drowned dozens of vehicles parked in an underground garage outside the terminal at Dallas Love Field Airport, where pools from 3½ inches of rain submerged some vehicles to their rooftops.
Parts of the Dallas-Fort Worth area received up to 7¼ inches (178 millimeters) of rain reported in Wylie.
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