Officials say a levee near a subdivision of homes in a county south of Houston has been breached and water is pouring into the area.
Brazoria County posted this message on Twitter on Tuesday morning: "NOTICE: The levee at Columbia Lakes has been breached!! GET OUT NOW!!!"
Brazoria County Judge Matt Sebesta says that the water has come over the levee in the northeast part of the subdivision and is starting to fill the area.
He says residents were told that at some point the levee would be "overtopped." He said that a mandatory evacuation order was issued Sunday.
Sebesta says there are hundreds of homes there. He says hopefully "very few" are still in the area.
The National Weather Service says rain is falling just east of Houston at a rate of 2 inches (5 centimeters) an hour.
The National Hurricane Center has said heavy rain from Harvey is forecast to worsen flooding in Southeast Texas and southwestern Louisiana.
NWS meteorologist Tawnya Evans says Harris County, home to Houston, is recording about half an inch (1 centimeter) of rainfall each hour early Tuesday, and that areas east of there are seeing much more.
She says the rain could abate later in the morning but that another band of heavy rainfall will soon follow.
Harvey is expected to produce 10 to 20 additional inches (25 to 51 centimeters) or rain over the upper Texas coast and southwestern Louisiana through Thursday.
The National Hurricane Center says heavy rain from Harvey is expected to worsen flooding in Southeast Texas and southwestern Louisiana.
The center says in its 4 a.m. CDT advisory that flooded roadways continue to make travel difficult and advises people to take shelter.
The center of the storm was marked 135 miles (220 kilometers) south-southwest of Port Arthur, Texas, and was moving east at 3 mph (4.8 kph) with sustained winds of up to 45 mph (72 kph).
The storm was expected to make a slow turn to the northeast on Tuesday, placing the center just off the middle and upper Texas Gulf coast through Tuesday night before moving inland. Harvey is expected to produce 10 to 20 additional inches or rain over the upper Texas coast and southwestern Louisiana through Thursday, with isolated storm totals maybe reaching 50 inches (130 centimeters) over the Houston-Galveston area and the upper Texas coast.
Crews overwhelmed by thousands of rescue calls during one of the heaviest downpours in U.S. history have had little time to search for other potential victims. But officials acknowledge the grim reality that fatalities linked to Harvey could soar once the devastating floodwaters recede.
Even worse, officials now worry that the worst may be yet to come.
More than three days after the storm ravaged the Texas coastline as a Category 4 hurricane, authorities worry that the tropical storm now parked over the Gulf Coast will return and deliver a knockout blow to a Houston region already ravaged by devastating downpours generating an amount of rain normally seen only once in more than 1,000 years.
Some fear that may be more than the nation's fourth-largest city could bear.
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