Death toll from US storms rises
Recovery teams have resumed the search for 12 members of two families who are missing after a rain-swollen river in Texas carried a holiday home off its foundation, slamming it into a bridge downstream.
In Houston, authorities recovered three more bodies from the floodwaters, bringing to 11 the number of people killed by the storms in Oklahoma and Texas.
A holiday weekend of storms dumped record rainfall on the American heartland, caused major flooding and spawned tornadoes.
More than 1,000 homes have been damaged or destroyed in Texas, and thousands of residents are displaced.
Authorities were also searching for victims and assessing damage just across the Texas-Mexico border in Ciudad Acuna, where a tornado on Monday killed 13 people and left at least five unaccounted for.
Houston mayor Annise Parker said officials in the nation's fourth largest city would be "on the alert" as the waters rise.
Texas governor Greg Abbott declared disasters in 37 counties, allowing for further mobilisation of state resources to assist.
"It's absolutely massive," Mr Abbott said after touring the destruction.
The worst flooding damage was in Wimberley, where the holiday home was swept away.
Witnesses reported seeing the swollen river push the home off its foundation and smash it into a bridge. Only pieces of the home have been found, Hays County Judge Bert Cobb said.
Judge Cobb had said on Monday night that one person who was rescued from the home told workers that the other 12 inside were all connected to two families. Young children were among those thought to be missing.
Early on Tuesday, Hays County spokeswoman Laureen Chernow said officials were not able to confirm whether all 12 people were in that house.
The Blanco river crested above 40ft (12 metres), more than triple its flood stage of 13ft.
The river swamped Interstate 35 and forced parts of the busy north-south highway to close. Rescuers used pontoon boats and a helicopter to pull people out.
In Austin on Monday, emergency crews responded to more than 20 high-water rescues. Harris County flood district, which includes Houston, advised residents not leave their homes after the weather service issued a flash flood warning for parts of the county.
Before the sun rose, emergency crews used helicopters and boats to help residents evacuate their flooded homes.
The four other Texas deaths included a man whose body was pulled from the Blanco; a 14-year-old who was found with his dog in a storm drain; a student whose car was caught in high water; and a man whose mobile home was destroyed by a reported tornado.
The Oklahoma department of emergency management reported four fatalities between Saturday and Monday across the state, which saw severe flooding and reported tornadoes.
US president Barack Obama said he has expressed his condolences over the Texas flooding situation to Mr Abbott.
Mr Obama said he told Mr Abbott he can count on the federal government for help. He said he anticipates significant requests for federal assistance.