Four children died and one is missing after a buggy carrying an Amish family was swept away by flood waters.

They were trying to cross a low-water bridge, but the current overwhelmed the vehicle.

Six people were in the horse and buggy on Wednesday in Bath County, Kentucky State Police said in a statement.

When they realised the water was too deep and tried to back the buggy up, the horse lost its footing and the buggy overturned.

The adult in the buggy was able to make it to the bank of the stream and call for help, police said.

Investigators say the accident happened approximately 4.20pm in the Salt Lick Community near Adams Road, north of Interstate 64.

The four siblings were found and pronounced dead by Bath County Coroner Andrew Owens on Wednesday.

Kentucky State Police Trooper Scott Ferrell said authorities from various agencies were continuing to search for the last missing child.

Missi Mosley and her boyfriend told WYMT-TV that they rushed to the scene on their ATV after hearing the call go out on the scanner.

“It was devastating,” Ms Mosley said. “The waters are so swift and the rain was pouring down. It was just a sombre feeling.”