HOUSTON(Reuters) - Torrential rains have killed at least eight people inTexasandOklahoma, including two in Houstonwhere flooding turned streets into rivers and led to nearly 1,000 calls for help in the fourth-most populous U.S. city, officials said on Tuesday.

 

Another 12 people were missing inTexasafter the storms slammed the states during theMemorial Dayweekend, causing floods and tornadoes that destroyed homes and swept away bridges.

 

"There are still some significant areas of really devastating flooding inHouston," MayorAnnise Parkersaid at a news conference, adding she has asked the governor to declare the city a disaster area.

 

She said most ofHoustonis high and dry but advised people to stay home.

 

PresidentBarack Obamasaid on Tuesday that he had assuredTexasGovernorGreg Abbottthat he could count on help from thefederal governmentas the state recovers from the floods. Abbott has declared a state of disaster in 24Texascounties.

 

There was no damage estimate available for the state, which has a $1.4 trillion-a-year economy and is the country's main domestic source of energy as well as an agricultural and manufacturing power.

More bad weather was expected with theNational Weather Serviceissuing aflashfloodwarning on Tuesday forHoustonas a line of thunderstorms moved along theGulf of Mexicocoast towardFlorida. It said there was a high chance of more rain and thunderstorms forTexasthis week.

Rescue workers looked for 12 members of two families missing after their vacation home was swept off its foundation inWimberley, a town about 30 miles southwest ofAustin, wherefloodwaters caused a wave of destruction.

"(People) have lost their homes, they have lost their livelihoods in some businesses," saidWimberleyMayorSteve Thurber.

One of those killed was an 18-year-old girl whose car was swept away byfloodwaters as she returned home from her high school prom, police in Devine,Texas, south ofSan Antonio, said.

More than 40 flights were canceled as of 10 a.m. CDT (1100 ET) at airports inHoustonandDallas, some of the nation's busiest, as blocked roads made it difficult for workers to get to their jobs. A sinkhole also closed a runway at theDallas/Fort Worth International airport, according to media reports.

About 100,000 customers were without power throughout the state due to high winds and rising waters that caused power poles to snap.

InHouston, Parker said there were about 1,000 vehicles had been submerged infloodwaters while inAustin, emergency crews used helicopters and boats to remove people from rushing water.