The incident was caused by heavy winds.
WASHINGTON - A tourist boat capsized and sank Thursday during a fierce storm on a lake in Missouri, killing at least 11 people, the local sheriff said.
The incident on Table Rock Lake that occurred as thunderstorms rumbled through the US Midwest left another seven people hospitalised while at least five were still missing, Stone County Sheriff Doug Rader told journalists, saying some of the dead were children.
The local branch of the Cox Medical Centre said two people were in critical condition, while the sheriff added several people had made it safely to shore.
Divers had arrived at the scene to assist in the search, Rader said, ending the rescue efforts for the night at approximately 11pm (0400 GMT Friday), with plans to reboot operations in the morning.
Rader said 31 people had been aboard the amphibious vessel, known as a duck boat for its wheels that allow it to ride on land in addition to floating low on the water.
He said the incident was caused by heavy winds, saying the tour boat had been making its way to land. Two boats had been on the water, according to Rader, one of which returned safely.
The man-made lake where the boat sank is a popular tourist draw located in southern Missouri near the city of Branson, on the border with Arkansas.
Rick Kettels, who owns the Lakeside Resort on the shores of Table Rock Lake, said the storm appeared to come out of nowhere.
"It just came up real quick," he told AFP, saying the storm struck around 6:15 pm local time.
"I've been here most of my life and I never saw a storm this bad," he added, saying he had not seen a warning from local weather stations.
'Big at its heart'
When the storm seemed imminent he had rushed to the lake to urge guests and boats to evacuate, as rough waves began slamming into his resort pier.
Steve Lindenberg, a meteorologist in Springfield, Missouri some 45 miles (72 kilometers) north of Branson, said a string of severe thunderstorms had barreled through the area causing significant tree damage and downed power lines.
At that office meteorologists had clocked winds at 74 miles per hour (119 kilometers per hour), issuing a warning to the area at approximately 6:30 pm.
The Branson airport had experienced a peak gust of 63 miles per hour, Lindenberg said.
"Our hearts are heavy tonight," the City of Branson said in a statement. "This is a very trying time for all those who are involved."
"The City of Branson may be small in size but it is big at its heart."
Branson's City Hall was open to victims, family membors and survivors, with support from the Red Cross as well as city officials.
The National Transportation Safety Board was to send a team early Friday to investigate the incident, the US agency said.
Branson, Missouri is a vacation destination popular for its theaters and country music, including singer Dolly Parton's Civil War-themed attraction.
The company Ripley Entertainment owns the capsized boat, having added Branson's "Ride the Ducks" attraction to its roster last year.
"Ride the Ducks" is a seasonal tour through the area's famed Ozarks region.
The incident in Missouri was part of a storm system that struck much of the Midwest late Thursday, according to meteorologists.
Several tornadoes tore through the state of Iowa just north of Missouri, causing injuries as well as structural damage to a number of buildings. No fatalities had been reported there.