The number of dead from Texas' devastating floods continues to rise, claiming two more lives in Houston overnight.

Houston Mayor Annise Parker confirmed the latest fatalities on Tuesday morning, leaving at least seven killed by the deluge in Texas and Oklahoma.

Swathes of America's fourth largest city have been inundated and dozens of vehicles left abandoned on swamped roads.

Fans at Monday night's Houston Rockets baseball game were told to stay in the Toyota Center arena until 3.50am because of the extreme weather.

Residents have been urged to stay off roads with many of the routes into Houston flooded and blocked by vehicles that have stalled.

The Houston Chronicle reports that some 52,000 householders are without power.

Hopes are meanwhile fading for 12 others who were in a house that was swept away on Sunday by raging floodwaters from the Blanco River, which is three times its normal level.

The holiday home in Wimberley, Texas, was lifted off its foundations and carried downstream where it slammed into a bridge.

Among the missing are Laura McComb and her two children - the distraught mother reportedly called her sister as the house was uprooted on Sunday.

The bad weather is among a line of storms that affected a large part of the US from the Gulf of Mexico to the Great Lakes.

Among the dead are homecoming queen Alyssa Ramirez, 18, who was swept away by floodwaters in Devine, southern Texas, as she drove home from her school prom on Saturday.

In DeSoto, Texas, a 14-year-old boy's body was found in a storm drain on Monday morning along with his dog.

In Claremore, Oklahoma, a firefighter was also swept into a storm drain while attempting a rescue on Sunday.

More than 1,000 homes have been damaged in Texas and 2,000 residents forced to leave their homes.

Texas Governor Greg Abbott, who has declared a disaster areas in 37 counties, said: "This is the biggest flood this area of Texas has ever seen.

"It is absolutely massive - the relentless tsunami-type power of this wave of water."

The region's wild weather brought a devastating tornado to a northern Mexican border city on Monday.

The whirlwind swept through Ciudad Acuna, flipping over cars, tearing down homes and ripping a child from its mother's arms.