The floods that ravage the Hill Country in Texas, USA, have claimed the lives of 24 people while more that 20 girls from a summer camp are missing.

Heavy rainstorms left almost one foot of rain (30 cm), forcing floodwaters spilling out of the Guadalupe River.

The rising waters flooded homes and swept away vehicles. Kerr County authorities said that at least 167 rescues by helicopter were carried out.

The number of people missing is not certain at the moment. Local authorities said that between 23 and 25 of them were girls who had been attending Camp Mystic, a Christian summer camp along the Guadalupe River.

AP reports that on social media, parents and families posted desperate pleas for information about loved ones who were caught in the flood zone.

“The camp was completely destroyed,” said Elinor Lester, 13, one of hundreds of campers at Camp Mystic. “A helicopter landed and started taking people away. It was really scary.”

The girl told AP that a raging storm woke her up at around 1:30 a.m. Friday, and when rescuers arrived, they tied a rope for the girls to hold as the children in her cabin walked across bridge with floodwaters whipping around the calves and knees.

Size of the flood was unexpected

The size and force of the flood was unexpected. The weather forecast had called for rain, but the heavy rainfall was beyond expectations, catching people unaware.

Original estimates were of up to 8 inches (20cm) of rain.

Bob Fogarty, meteorologist with the National Weather Service’s Austin/San Antonio office, said that a river gauge at Hunt recorded a 22 foot rise (6.7 meters) in about two hours, and failed after recording a level of 29 and a half feet (9 meters). He said that the water moves so fast that you will realize only when it covers you.

Texas Lieutenant Governor Dan Patrick said: “Within 45 minutes, the Guadalupe River rose 26 feet and it was a destructive flood, taking property and sadly lives.”

Helicopters and paddle boats were used to rescue people who were desperate to escape the rising waters. Officials said search and rescue operations, involving helicopters, drones and boats, would continue until everyone had been accounted for.

A state of emergency has been declared in several Texas counties where several roads have been washed away and phone lines are down. Pictures show the deep flood waters swamping bridges and fast moving water swirling down roads.

US President Donald Trump called the tragedy “shocking” and “terrible” as the White House pledged additional assistance to the area.