An amphibious vehicle has capsized on a lake in Missouri with over 20 people on board, leading to a "mass casualty incident," according to Southern Stone County Fire Protection District.

Several people were taken to hospital following the incident on the "Ride the Ducks" amphibious vehicle on Table Rock Lake, Stone County, near Branson, Missouri, the fire district said in posts on Twitter.

Stone County Sheriff Doug Rader said there were fatalities when the boat carrying 31 people, some of them children, capsized and sank, television station KY3 News reported.

Rader said he did not know how many people died, and divers were on the scene searching for passengers, KY3 News reported.

The Stone County Sheriff's Office could not immediately confirm the report.