Dozens of people are missing from a girls' summer camp in Texas amid flash flooding that has left at least 50 people dead.
The state's Kerr County was most affected, authorities said on Saturday, with 43 people confirmed dead, including 15 children.
"We will not stop until every single person is found," Kerr County Sheriff Larry Leitha said at a news conference.
More than 800 people had been evacuated in the area, about 100 kilometres north-west of San Antonio and 130km west of Austin, the sheriff's office in Kerr County said.
Meanwhile, seven other people died across the Travis, Burnet and Tom Green counties, according to an AFP tally of figures provided by local officials.
Camp Mystic girls still missing
There are 27 young girls from the Camp Mystic summer camp still missing.
"We are kind of looking at this in two ways called the known missing, which is the 27 … We will not put a number on the other side because we just don't know," the sheriff said.
Two nine-year-old campers who went missing from the camp have been confirmed among the dead.
"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."
The teen woke up in her cabin in the middle of the night.
When rescuers arrived, they tied a rope for the girls to hold as they walked across a bridge with water around their legs, she said.
The Christian summer camp is located near the Guadalupe River, where the waters rose eight metres in just 45 minutes.
Texas Lieutenant Governor Dan Patrick said Camp Mystic had 700 girls on site at the time of the flood.
The US National Weather Service said the flash flood emergency had largely ended for Kerr County, the epicentre of the flooding.
A flood watch remained in place for the broader region following thunderstorms that dumped as much as 300 millimetres of rain — half the region's average annual total.
In 36 hours first responders have rescued more than 850 people, with some residents plucked from rooftops and trees," the Kerr County Sheriff said.
'Unknown number of missing people'
The Guadalupe River is a popular location for youth camps and campgrounds, where families go to swim and enjoy the outdoors.
Texas Lieutenant Governor Dan Patrick said up to 500 rescue workers were searching for an unknown number of missing people due people heading to the area for the July 4 holiday.
"We don't know how many people were in tents on the side, in small trailers by the side, in rented homes by the side, because it was going to be the Fourth of July holiday," he said on Fox News Live.
Another girls' camp, Heart O' the Hills, said on social media that co-owner Jane Ragsdale had died in the flood but no campers had been present as it was between sessions.
A firefighter was among the missing after he was swept away by floodwaters while responding to a call, county emergency management coordinator Derek Marchio said.
'No-one saw this coming'
Local resident and Kerr County Judge Rob Kelly said his house, located on the Guadalupe River, was lost in the floods.
"I barely got home yesterday," he says.
Kerrville city manager Dalton Rice said the extreme flooding struck before dawn with little or no warning.
The Guadalupe River rose above major flood levels in less than two hours, preventing authorities from sending out advanced evacuation orders, he said.
Emergency officials had warned as early as Thursday that west and central Texas faced heavy rains and flash flood threats, citing National Weather Service forecasts ahead of the holiday weekend.
The forecasts, however, "did not predict the amount of rain that we saw," W Nim Kidd, director of the Texas Division of Emergency Management said.
US President Donald Trump said the federal government is working with state and local officials to respond to the flooding.
"Melania and I are praying for all of the families impacted by this horrible tragedy. Our Brave First Responders are on site doing what they do best," he said on social media.
Mr Trump has previously outlined plans to scale back the federal government's role in responding to natural disasters, leaving states to shoulder more of the burden themselves.
Responding to the disaster, Texas Governor Greg Abbott declared Sunday a "day of prayer" in the state.
ABC/wires
