Texas Governor Greg Abbott has warned that severe flooding is his main worry as the rains from Tropical Storm Harvey continue to lash the state.
Mr Abbott said the cities of Houston and Corpus Christi had already received as much as 20in (50cm) of rain.
He said another 40in of rain could be due before the storm subsides midweek.
Rescue efforts are being hampered by strong winds and thousands are without power. Two deaths have been confirmed, in the Rockport area and Houston.
In Aransas County, where Rockport is the chief town, a person died in a house fire on Friday night
A woman died in Houston as she drove through flooded streets on Saturday
Houston, the fourth biggest city in the US, could see 2in-3in (5cm-7.5cm) of a rain an hour on Saturday night, Mayor Sylvester Turner said.
About 4,500 inmates from prisons south of Houston are being evacuated to other prisons in east Texas because the Brazos River nearby is rising significantly, officials say.
In the wreckage of Rockport locals are the first responders.
Residents have been going door-to-door checking to see if their neighbours are dead or alive.
The little town has not been destroyed but it is in bad shape, particularly in the poorer quarters where trailer homes have been smashed open by the wind.
Debris is trailing from the tops of trees and on the porch of one modest property a rain-sodden American flag lies on the ground: a splash of red, white and blue amid the green leaves of fallen trees.
Most people appear to have got out just in time with many leaving only at the last minute as the full power of the storm became clear.

(Source: BBC)