Houston Flood

Houston floods: "Worst not yet over," says Texas governor

He said rain continues to fall and flooding in certain areas may last another week.

More than 20 people are reported dead, and large parts of the city of Houston are under water.

The storm has now moved on to neighbouring Louisiana, where flash-flood warnings have been issued.

Governor Abbott said Texas has carried out more than 8,500 rescues, and more than 32,000 people remain in shelters throughout the state.

Another 10,000 members of the National Guard are said to be on their way, joining the 14,000 already deployed to tackle the disaster.

Beyonce offers aid to Houston flood victims

"I remain in constant prayer for those affected and for the rescuers who have been so brave and determined to do so much to help," the star said.

She added that she was working with her charity and her pastor "to implement a plan to help".

Houston has been hit by unprecedented levels of rain, with more set to come.

Officials estimate that more than 30,000 residents need shelter. At least nine have died in the Houston area.

Other stars including Kim Kardashian West and Kevin Hart have also vowed to help.