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A duck boat capsized and sank during a severe thunderstorm in Missouri, killing at least 11 people, some of them children, authorities said.

Stone County Sheriff Doug Rader said 31 people were aboard the boat during Thursday night’s incident on Table Rock Lake near Branson. Six people are unaccounted for and 14 survived, he said.

Video posted by Jennie Phillips-Hudson Carr and shot from a nearby larger vessel showed two duck boats rocking and tilting to the side as the lake’s ripples turned into massive waves.

“Oh my God, those poor people, oh no!” someone says in the background as the water crashes into the bobbing boats.

“If there’s kids on there, those poor babies,” a female voice says.

Diving teams from various agencies scoured the waters for potential victims, and will resume again in the morning.

The duck boat had life jackets

An off-duty deputy working security helped rescue people, Rader said, without providing details. He said there were life jackets aboard the boat, but he doesn’t know whether people were wearing them.

Ripley Entertainment, the parent company of Ride the Ducks Branson, said it recently acquired the vessel involved in the incident. It said there were other boats on the lake that returned to dock safely.

Rader confirmed that there were two duck boats headed toward land, but one made it out safely.

The amphibious boat travels on both land and water, and is popular among tourists in major cities. The boats’ history dates back to World War II, when such boats were a common sight due to their versatility.

Severe thunderstorms hit Branson

Branson was under a severe thunderstorm warning issued shortly before 6:30 p.m. local time, about half an hour before the boat capsized.

There were numerous reports of damage throughout the county, including trees down and structural damage, said CNN meteorologist Taylor Ward. The highest wind gust reported in the area was 63 mph.

“I believe it was caused by weather, yes,” said Rader, the sheriff.

Gov. Mike Parson asked for prayers for first responders and those involved in the incident.

The investigation will be conducted by the Coast Guard, said Sgt. Jason Pace of the Missouri State Highway Patrol, which is assisting. A team from the National Transportation Safety Board will travel to the scene Friday morning.

Branson is about 200 miles from Kansas City, and is considered a major family vacation destination.

27 reported tornadoes rip through Iowa

CNN’s Deanna Hackney, Steve Almasy and Sheena Jones contributed to this report.