Police have confirmed the deaths of at least 13 people after a popular tourist activity ran into difficulty.
A total of 31 people had been on board the boat, which was sailing on Table Rock Lake in Branson, Missouri.
High winds caused the boat to become laden with water and capsize.
Emergency crews were called to the incident shortly after 7:00pm (12:00am Friday BST) on Thursday.
Branson is a highly popular tourist attraction, with 7.2 million visitors every year.
The midwestern town is known for its country music and family-friendly attractions.
Table Rock Lake is a reservoir measuring 67-square-miles with water from the Table Rock Dam on the White River.
Duck boats are a popular attraction to tourists, taking tours of the reservoir.
“This is a really tough situation and it’s gut-wrenching,” city spokeswoman Melody Pettit told a news conference outside Branson city hall. “But we are doing our best to try to help.”
Weather conditions caused waves to become choppy, and boats across the lake struggled to stay afloat.
Stone County Sheriff Doug Rader told of how one of his deputies was on the boat at the time and had managed to help rescue some of the passengers.
“There was some heavy wind. It was having problems through the wind,” Mr Rader told reporters.
“They were coming back toward land. There was actually two ducks. The first one made it out. The second one didn’t.”
What is a duck boat?
Duck boats are designed around boats used in World War Two to carry soldiers and supplies across water and land.
These military vessels were known as DUKW and were first made in the United States in the mid-1940s.
The boats are actually six-wheel amphibious trucks and were used when broaching a shore which had no ports.
Are duck boats dangerous?
The boats are highly popular with tourists all over the world and have given tours for a number of years.
There have been some fatalities caused by duck boats, however, despite a number of high profile incidents, these are rare.
The most serious incident occurred in 1999 when a duck boat sunk moments after launching onto Lake Hamilton in Arkansas and was reported as “uncontrolled flooding” due to a loose part.
The resulting tragedy saw 13 people killed, which included three children.
In 2015, five students were killed and dozens of others injured when a duck boat struck a bus in Seattle.
This was due to one of the vehicle’s axels having “sheared off” according to a report from NTSB.
A year later in 2016, a woman died when her motorcycle collided with an amphibious vehicle in Boston.