Flood in 'most dangerous valley' in US' Texas: How Guadalupe River surged 26 feet in 45 minutes

A "catastrophic" flash flood has killed at least 24 people in south-central Texas, with the authorities desperately searching for at least 20 girls missing from a riverside summer camp. The floods were triggered by torrential rains in what the authorities described as the "most dangerous river valley in the United States".

"At this point, we're at about 24 fatalities," Kerr County Sheriff Larry Leitha told a press conference as rescue teams scrambled to locate stranded residents in the region northwest of San Antonio.

Texas Lieutenant Governor Dan Patrick said that some of the deceased were children. Another official said that around 25 people were missing.

The missing girls were part of a group of around 750 children at Camp Mystem, a summer camp for girls. The flash flood was triggered after the Guadalupe River rose 26 feet (eight meters) in 45 minutes.

However, the officials hope that the missing girls could be "in a tree or just out of communication".

Texas Governor Greg Abbott said he was signing a "disaster declaration" to boost resources in the affected region.

Around 500 personnel and 14 helicopters had been pressed into the rescue operation. At least 237 people had been rescued or evacuated by emergency personnel.

Houses were sweptaway by the flash flood, which was caused by heavy overnight rain. The rain of up to 12 inches – one-third of Kerr County's annual average – caused the sudden swelling in the river.

Governor Abbott said the authorities would not stop the search until "everyone is accounted for".

Public safety official Martin warned of "another wave" that could impact other counties in the state, adding that "this is not going to end today".

The local officials weren't forewarned about the floods. "We didn't know this flood was coming," Kerr County Judge Rob Kelly said on Friday.

"This is the most dangerous river valley in the United States," he added, referring to the Guadalupe River.

Meanwhile, forecasters have issued a flood warning for the county. They have asked those living near the river to move to higher ground.