The death toll of Central Texas flood has killed 51 while more than 20 people remained missing as of Saturday night, according to the authorities.

At least 15 of the confirmed dead were children, many of were attending Camp Mystic, a Christian girls' camp.

The flood came in the early morning on July 4, the Independence Day. About 10 inches of water increased the water level in some section of the Guadalupe River by more than 20 inches, leading to riverbank overflow that swept away trailer houses while they were sleeping.

Most of the missing persons were young girls from Camp Mystic in Kerr County where the flood killed the most. A few hundred children were attending this camp when the flood happened.

Another camp by the Guadalupe River Heart O' Hills announced that its director and co-owner Jane Ragsdale was also killed in the flood. Luckily all the children attending the camp got out in time.

A local boy soccer coach, his wife and their two children perished in the flood. A 27-year-old man managed to save his family including his mother, fiancée and their children but died in the effort.

State official said that more than 800 people have been rescued so far. Texas Governor Greg Abbott has issued disaster declaration for 15 counties in the region.

While vowing continuous searching until every missing one is accounted for, officials did acknowledge that as times goes by, the chance of finding survivors are diminishing. That means the final death toll could exceed 70.

Kerr County Judge Rob Kelly said on Friday that "no one knew this kind of flood was coming". Flood warning came in the dead of the night shortly after 1 am, about three hours before the riverbank was overflown. People were caught off guard completely.

City Manager Dalton Rice of Kerrville said that the extent and scale of the flood was unprecedented. "From our flood maps, we're seeing some areas where it's hitting the 100-year flood thing," said Rice at a Saturday evening news conference, meaning the chance of such flood is one percent.

The Kerr County and its surrounding region is part of Texas Hill Country, known for its natural beauty but also has a history of flash flood. Many came and camped along the Guadalupe River to celebrate the Independence Day.