Texas officials warned of a health crisis on Monday and urged thousands of people to leave Galveston, where relief supplies were scarce for hungry, exhausted residents of the island city ravaged by Hurricane Ike.
In Houston, millions struggled to cope without power in the U.S. energy hub.
About 2,000 people have been plucked from flooded areas by helicopters and boats in the largest rescue effort in the state's history as searchers scoured battered communities along the coast and Galveston Bay.
Galveston, a city of 60,000, was decimated when the hurricane made landfall there on Saturday morning and 15,000-20,000 people remained in quickly degrading conditions.
"There's nothing to come here for," Galveston Mayor Lyda Ann Thomas told residents still on the island.
