Dozens have been killed in the US state of Texas after heavy rain caused flash flooding, with 27 missing from a children's camp.

Texas parents frantically posted photos of their young daughters on social media with pleas for information as at least 27 campers from an all-girls summer camp were unaccounted for Friday after floods tore through central Texas overnight.

(Reuters) -Torrential rains unleashed flash floods along the Guadalupe River in Texas on Friday, killing at least 24 people as rescue teams scrambled to save dozens of victims trapped by high water or reported missing in the disaster, local officials said.