Among the missing were about two dozen people listed as unaccounted for at an all-girls Christian summer camp located on the banks of the Guadalupe River, authorities said.
Texas parents frantically posted photos of their young daughters on social media with pleas for information.
Search teams used helicopters and drones through the night to look for victims and rescue people who were stranded. The danger was not over as more heavy rains were expected on Saturday and flash flood warnings and flood watches remained in effect for parts of central Texas.
Authorities have come under intense scrutiny over whether the camp and others in the area received sufficient, if any, warning and whether enough preparations were made.
AccuWeather, a private forecasting company, said it and the National Weather Service sent warnings about potential flash flooding hours before the devastation.
The destructive fast-moving waters along the Guadalupe River rose eight metres (26 feet) in just 45 minutes before dawn on Friday, washing away homes and vehicles.
Hundreds of rescuers were deployed around Kerr County as part of a massive search-and-rescue operation, including at least 167 working by helicopter, authorities said.
The National Weather Service declared a flash flood emergency for parts of the county, located in south-central Texas Hill Country, about 105km (65 miles) northwest of San Antonio, following heavy downpours measuring up to 300mm (12 inches) of rain.
Screengrab shows first responders surveying the rising floodwaters of the Guadalupe River after flash flooding in Kerr County, Texas, on July 4, 2025 [ABC Affiliate KSAT via Reuters]
Dalton Rice, city manager for Kerville, the county seat, told reporters the extreme flooding struck before dawn with little or no warning, precluding authorities from issuing any evacuation orders.
“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.”
On Friday, Lieutenant Governor Dan Patrick said 23 girls were listed as unaccounted for among more than 700 children who were at the summer camp when it was swept by floodwaters at about 4am local time (09:00 GMT).
“That does not mean they’ve been lost; they could be in a tree, they could be out of communication,” he said.
“Some are adults, some are children,” Patrick said. “Again, we don’t know where those bodies came from.” Patrick read out a message from the director of the summer camp, which had some 750 campers over the July 4 holiday weekend, reporting that it had “sustained catastrophic level of flooding”.
“We have no power, water or Wi-Fi,” the message said.
State and local officials warned against residents travelling to the area, which includes campgrounds dotted along the river, with dozens of roads “impassable”.
Videos on social media showed houses and trees swept away by the overnight flash flood caused by heavy overnight rainfall of 300mm – one-third of Kerr County’s average annual rainfall.
“It’s terrible, the floods,” US President Donald Trump told reporters Friday night. “It’s shocking.”
Texas Governor Greg Abbott signed a disaster declaration to hasten emergency assistance to Kerr and a cluster of additional counties hardest hit by the floods.
