Families sifted through waterlogged debris on Sunday and stepped inside empty cabins at Camp Mystic, an all-girls summer camp ripped apart by flash floods that washed homes off their foundations and killed at least 78 people in central Texas.

Rescuers manoeuvring through challenging terrain continued their desperate search for the missing, including 10 girls and a counsellor from the camp. For the first time since the storms began pounding Texas, Gov. Greg Abbott said there were 41 people confirmed to be unaccounted for across the state and more could be missing.

In Kerr County, home to Camp Mystic and other youth camps in the Texas Hill Country, searchers have found the bodies of 68 people, including 28 children, Sheriff Larry Leitha said on Sunday afternoon.

He pledged to keep searching until"everybody is found" from Friday's flash floods. Ten other deaths were reported in Travis, Burnet, Kendall, Tom Green and Williamson counties, local officials said.

The death toll is certain to rise over the next few days, said Col. Freeman Martin of the Texas Department of Public Safety.

The governor warned on Sunday that additional rounds of heavy rains lasting into Tuesday could produce more life-threatening flooding, especially in places already saturated.

Families were allowed to look around the camp beginning Sunday morning. One girl walked out of a building carrying a large bell. A man, who said his daughter was rescued from a cabin on the highest point in the camp, walked a riverbank, looking in clumps of trees and under big rocks.

A woman and a teenage girl, both wearing rubber waders, briefly went inside one of the cabins, which stood next to a pile of soaked mattresses, a storage trunk and clothes. At one point, the pair doubled over, sobbing before they embraced.

One family left with a blue footlocker. A teenage girl had tears running down her face looking out the open window of a vehicle, gazing at the wreckage as they slowly drove away.

Searching the disaster zone

While the families saw the devastation for the first time, nearby crews operating heavy equipment pulled tree trunks and tangled branches from the water as they searched the Guadalupe River.

With each passing hour, the outlook of finding more survivors became even more bleak. Volunteers and some families of the missing who drove to the disaster zone searched the riverbanks despite being asked not to do so.

Authorities faced growing questions about whether enough warnings were issued in an area long vulnerable to flooding and whether enough preparations were made.

U.S. President Donald Trump signed a major disaster declaration on Sunday for Kerr County, activating the Federal Emergency Management Agency (FEMA) to Texas.

The president said he would likely visit on Friday."I would have done it today, but we'd just be in their way," he told reporters before boarding Air Force One back to Washington after spending the weekend at his golf club in Bedminster, N.J. "It's a horrible thing that took place, absolutely horrible."

The destructive, fast-moving waters of the river rose eight metres in only 45 minutes before daybreak on Friday, washing away homes and vehicles. The danger was not over as flash flood watches remained in effect and more rain fell in central Texas on Sunday.

Searchers used helicopters, boats and drones to look for victims and to rescue people stranded in trees and from camps isolated by washed-out roads. Officials said more than 850 people were rescued in the first 36 hours.

Prayers in Texas — and from the Vatican

Abbott, the state's governor, vowed that authorities will work around the clock and said new areas were being searched as the water receded. He declared Sunday a day of prayer for the state.

"I urge every Texan to join me in prayer this Sunday — for the lives lost, for those still missing, for the recovery of our communities, and for the safety of those on the front lines," he said in a statement.

In Rome, Pope Leo XIV offered special prayers for those touched by the disaster. History's first American pope spoke in English at the end of his Sunday noon blessing: "I would like to express sincere condolences to all the families who have lost loved ones, in particular their daughters who were in summer camp, in the disaster caused by the flooding of the Guadalupe River in Texas in the United States. We pray for them."

The hills along the river 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 Independence Day holiday, making it more difficult to know how many are missing.

Harrowing escapes from floodwaters

Survivors shared terrifying stories of being swept away and clinging to trees as rampaging floodwaters carried trees and cars past them. Others fled to attics inside their homes, praying the water wouldn't reach them.

At Camp Mystic, a cabin full of girls held onto a rope strung by rescuers as they walked across a bridge with water whipping around their legs.

Among those confirmed dead were an eight-year-old girl from Mountain Brook, Ala., who was at Camp Mystic, and the director of another camp up the road.

Two school-age sisters from Dallas were missing after their cabin was swept away. Their parents were staying in a different cabin and were safe, but the girls' grandparents were unaccounted for.

Locals know the Hill Country as" flash flood alley," but the flooding in the middle of the night caught many campers and residents by surprise even though there were warnings.

Warnings came before the disaster

The National Weather Service on Thursday advised of potential flooding and then sent out a series of flash flood warnings in the early hours of Friday before issuing flash flood emergencies — a rare alert notifying of imminent danger.

At the Mo-Ranch Camp in the community of Hunt, Texas, officials had been monitoring the weather and opted to move several hundred campers and attendees at a church youth conference to higher ground. At nearby Camps Rio Vista and Sierra Vista, organizers had mentioned on social media that they were watching the weather the day before ending their second summer session on Thursday.

Authorities and elected officials have said they did not expect such an intense downpour, the equivalent of four months' worth of rain for the area.

Kerrville city manager Dalton Rice said authorities are committed to a full review of the emergency response, including how the public was alerted to the storm threat.

Trump, asked whether he was still planning to phase out FEMA, said that was something"we can talk about later, but right now we are busy working." He has previously said he wants to overhaul if not completely eliminate the agency and has been sharply critical of its performance.

He was also asked whether he planned to rehire any of the federal meteorologists who were fired this year as part of widespread government spending reductions.

"I would think not. This was a thing that happened in seconds. Nobody expected it. Nobody saw it. Very talented people there, and they didn't see it," the president said.