Houston Mayor Sylvester Turner said on Saturday night the city could receive as much as two to three inches (five to seven and a half centimeters) of rain per hour in the upcoming hours due to Tropical Storm Harvey.
"We got a break for several hours during the day (but) several rainbands will be coming through tonight. Please be alert," he tweeted.
Turner urged the residents of Houston to be attentive to weather reports and added, “The weather system is very unpredictable but will produce rain over several days. Red Cross and City decided to open a few shelters now.”
“Please stay off the roads unless it is an emergency. You are safer at home,” he added.
Harvey hit the Texas coast on Friday night as a Category 4 hurricane with winds gusting at 130 miles per hour.
Though people are trapped in buildings, the exact number of victims is not yet known. At least one of the trapped victims died when a fire broke out during the storm.
The storm was downgraded from a hurricane to a tropical storm earlier on Saturday.
Harvey is the U.S. mainland's worst stormsince Hurricane Wilma in 2005.
The Jewish community in Houston was forced to cancel services and other community activities due to the storm.