At least 15 people are reported to have been killed after severe flooding and wild weather across Texas and Oklahoma in the US.
Floodwaters swept through as many as 400 homes in the city of Austin, Texas.
In Houston, more than 25 centimetres of rain fell in just a few hours, triggering the worst flooding in a decade and leaving large parts of the country's fourth most populous city underwater.
The Houston Fire Service was forced to use boats to bring up to 500 people to safety.
Thousands of residents have been displaced and over 1000 homes were destroyed, the BBC reported.
Houston Mayor Annise Parker said at a news conference that most of the city was high and dry but there were still "some significant areas of really devastating flooding".
She advised people to stay home and not seek out the floodwaters for photos.
"Last night, we had torrential rain, localised street flooding, so we had a lot of folks who had to abandon cars and we had a lot of high-water rescue from vehicles," she said.
"This morning, the small rivers that run through the city went over their banks and began to flood neighbourhoods."
Texas Governor Greg Abbott has declared a state of emergency in 24 of the state's counties.
He said he had deployed the state's national guard and was worried the death toll could rise. "We still have countless people who are missing," he told CNN.
Twelve people have been confirmed missing and about another 30 were unaccounted for due to flooding that hit along the Blanco River in central Texas, county officials said.
The missing were from two families whose vacation home was swept off its foundation in Wimberley, a town about 50 km southwest of Austin.
"We are floating in a house that is now floating down the river", one missing family member, Laura McComb, told her sister Julie Shields, according to local TV station KXAN. "Call Mom and Dad. I love you, and pray".
Laura's husband Jonathan McComb escaped the floodwaters, his father Joe McComb told the Washington Post.
One of those killed was an 18-year-old girl whose car was swept away by floodwaters as she returned home from her high school prom, police in Devine said.
President Barack Obama has pledged federal aid to help the two states recover.
On Tuesday, at least 14 people - including an infant - were killed by a tornado that hit the northern Mexico border city of Acuna.
Mexican authorities said that more than 1000 homes were damaged by the storm.
- Reuters / BBC