Columbia Lakes residents in Brazoria County were evacuating immediately, following orders from county officials.
Brazoria County officials said they expect widespread flooding of the Brazos River after the levee breach at Columbia Lakes.
The Brazos River has risen to historic heights as a result of storm Harvey and caused the levee to fail Tuesday, a scenario that authorities feared.
Two Houston reservoirs are overflowing, despite a controlled water release that tried to prevent flooding downtown. However, the releases couldn't keep up with the fast rising water levels.
Jeff Lindner, with the Harris County Flood Control District, told CBS News he's sure more properties will flood. Some levees in outlying areas are created to protect against flooding that happens every 100 or 200 years.
Earlier on Tuesday, a report by local ABC affiliate KTRK indicated the Addicks Reservoir due west of Houston might spill over for the first time in its history.
Thousands of people are in danger as they try to escape. Instead, the pair are to visit the hard-hit city of Corpus Christi - close to where the hurricane - later downgraded to a tropical storm - made landfall on Friday.
Brazoria County is located about 50 miles south of Houston, which has taken a brunt of the flooding damage.
One Houston woman said she presumes six members of a family, including four of her grandchildren, died after their van sank into Greens Bayou in East Houston. The previous death toll allocated to the weather system was three.