At least 11 people, including several children, have died after a boat carrying tourists capsized and sank on a lake during a thunderstorm in south-west Missouri.

The Stone County Sheriff’s office said six people remain missing after the Ride the Ducks boat sank on Table Rock Lake in Branson on Thursday night, with seven others taken to hospital.

Divers were expected to resume their searching for the missing early on Friday.

A spokeswoman for the Cox Medical Centre in Branson said four adults and three children arrived at the hospital shortly after the incident. Two adults are in a critical condition and the others were treated for minor injuries, Brandei Clifton said.

Sheriff Doug Rader said stormy weather likely made the boat capsize. Another duck boat on the lake made it safely back to shore.

Steve Lindenberg, a National Weather Service meteorologist in Springfield, Missouri, said the agency issued a severe thunderstorm warning for the Branson area Thursday evening. Lindenberg said winds reached speeds of more than 60mph.

“It’s a warning telling people to take shelter,” he said.

Sheriff Rader said an off-duty sheriff’s deputy working security for the boat company helped rescue people after the boat capsized. Dive teams from several law enforcement agencies assisted in the effort.

The National Transportation Safety Board said investigators will arrive on the scene on Friday morning.

Suzanne Smagala with Ripley Entertainment, which owns Ride the Ducks in Branson, said the company was assisting authorities with the rescue effort.

Ms Smagala added this was the Branson tour’s only accident in more than 40 years of operation.

Branson is about 200 miles south-east of Kansas City and is a popular vacation spot for families and other tourists looking for entertainment ranging from theme parks to live music.

An EF2 tornado that tore through Branson in 2012 destroyed dozens of buildings and injured about three dozen people, but killed no-one.

Duck boats, which can travel on land and in water, have been involved in other deadly incidents in the past. Five college students were killed in 2015 in Seattle when a duck boat collided with a bus, and 13 people died in 1999 when a duck boat sank near Hot Springs, Arkansas.

Safety advocates have sought improvements since the Arkansas deaths. Critics argued that part of the problem is that too many agencies regulate the boats with varying safety requirements.

Duck boats were originally used by the US military in the Second World War to transport troops and supplies, and later were modified for use as sightseeing vehicles.