Hundreds of rescuers have been deployed to search for survivors in central Texas, after flash floods killed 43 people, including 15 children.

“The work continues, and will continue, until everyone is found,” promised Larry Leitha, the sheriff of Kerr County.

As the search goes into a second night, county officials said 27 children remained missing from a Christian youth camp located along the river.

Some parents confirmed their child’s death on social media. About 850 people have been rescued so far.

Multiple flash flood warnings remain in place over the weekend in central Texas.

At a press conference on Saturday afternoon, Texas Governor Greg Abbott said he had signed an expanded disaster declaration to boost search efforts.

He said officials would be relentless in ensuring they locate “every single person who’s been a victim of this event”, adding that “we will stop when job is completed”.

It remains a search and rescue mission, officials said, not a recovery effort.

They said rescuers were going up and down the Guadalupe River to try to find people who may have been swept away by the floods.

US President Donald Trump said his administration is working closely with local authorities to respond to the emergency.

Homeland Security Secretary Kristi Noem said the federal government would deploy the Coast Guard to help search efforts.

Forecasters have warned that central Texas may see more flooding this weekend.

The National Weather Service (NWS) said the area could see 2 to 5in (5cm to 12cm) of rain on Saturday.

Up to 10in of rain was possible in some areas badly affected by Friday’s deluge.

Much of the rescue has focused on a large all-girls’ Christian summer camp called Camp Mystic, located along the banks of the Guadalupe River.

Texas Lieutenant Governor Dan Patrick told the BBC’s Radio 4 PM programme many of 27 missing girls were “under the age of 12”.

Pictures from the camp show it in disarray, with blankets, mattresses, teddy bears and other belongings caked in mud.

Many were asleep when the river rose more than 26ft (8m) in less than an hour in the early hours of Friday.

In an email to parents of the roughly 750 campers, Camp Mystic said that if they haven’t been contacted directly, their child is considered missing.

Some of the families have already stated publicly that their children were among those who were found dead.

A special mass will be held at Notre Dame Catholic Church on Sunday for those who died or are missing, and their families.

Scores of campers holidaying during the 4 July weekend, were also unaccounted for.

Lorena Guillen, whose home and restaurant were destroyed, had 28 recreational vehicles staying on her land near the river. She told the BBC News Channel that she heard screams from a family of five.

“They were getting washed away,” Guillen said. “They were clinging on trees to be rescued. But the rescuers couldn’t get to them”.

Rachel Reed drove five hours from Dallas to pick up her daughter. She told the BBC that members of her church and children’s school district were among the girls dead and missing.

“The families of those campers are living every parent’s worst nightmare,” she said. “Of course, it could have been me.”

Others started returning to the flooded areas.

Jonathan and Brittany Rojas visited their relatives’ home – where only the foundation remained.

They told the BBC that the mother and a baby of the family remained missing. A teenage son, Leo, survived after he became snared in barbed wire.

Another resident, Anthony, found his apartment full of mud and debris. His belongings were not salvageable, except a box holding childhood photos and his baby blanket.

“I lost everything I own,” he told the BBC. “Now I’m trying to figure things out.”

Additional reporting by Iona Hampson in Texas and Ana Faguy in Washington.