More than 850 people had been rescued, including some who were clinging to trees, after a sudden storm dumped up to 38cm of rain in an area around the Guadalupe River, about 140km northwest of San Antonio.
Some 36 hours after the floods, authorities have still haven't said how many people are still missing beyond the 27 children from Camp Mystic, a Christian summer camp along the river.
The destructive fast-moving waters rose eight metres in just 45 minutes before daybreak on Friday, washing away homes and vehicles.
The danger was not over as torrential rains continued pounding communities outside San Antonio on Saturday and flash flood warnings and watches remained in effect.
Searchers used helicopters, boats and drones to look for victims and to rescue stranded people in trees and from camps isolated by washed-out roads.
"We will not stop until we find everyone who is missing," Nim Kidd, chief of Texas Department of Emergency Management, said at a press conference on Saturday afternoon.
Kerr County Sheriff Larry Leitha said the bodies of 32 people had been recovered so far: 18 adults and 14 children.
Authorities were coming under growing scrutiny over whether the camps and residents in places long vulnerable to flooding received proper warning and whether enough preparations were made.
The hills along the Guadalupe River in central Texas are dotted with century-old youth camps and campgrounds where generations of families have come to swim and enjoy the outdoors. The area is especially popular around the July Fourth holiday, making it more difficult to know how many are missing.
"We don't even want to begin to estimate at this time," said City Manager Dalton Rice said on Saturday.
"The camp was completely destroyed," said Elinor Lester, 13, one of hundreds of campers.
"A helicopter landed and started taking people away. It was really scary."
A raging storm fuelled by incredible amounts of moisture woke up her cabin just after midnight Friday, and when rescuers arrived, they tied a rope for the girls to hold as they walked across a bridge with water whipping around their legs, she said.
Frantic parents and families posted photos of missing loved ones and pleas for information.
On Saturday, the camp was mostly deserted. Helicopters roared above as a few people looked at the damage, including a pickup truck tossed onto its side and a building missing its entire front wall.
Among those confirmed dead were an eight-year-old girl from Mountain Brook, Alabama, who was staying at Camp Mystic and the director of another camp just up the road.
The flooding in the middle of the night caught many residents, campers and officials by surprise in the Hill Country, which sits northwest of San Antonio.
AccuWeather said the private forecasting company and the National Weather Service sent warnings about potential flash flooding hours before the devastation.
"These warnings should have provided officials with ample time to evacuate camps such as Camp Mystic and get people to safety," AccuWeather said in a statement that called the Hill Country one of the most flash-flood-prone areas of the US because of its terrain and many water crossings.
Officials defended their actions while saying they had not expected such an intense downpour that was the equivalent of months' worth of rain for the area.
One National Weather Service forecast earlier in the week "did not predict the amount of rain that we saw", said Nim Kidd, chief of the Texas Division of Emergency Management.
Search crews were facing harsh conditions while "looking in every possible location", Rice said.
with reuters
