At least 11 people have died after an amphibious “duck boat” carrying tourists sank in stormy weather in the US state of Missouri, police say.
The vessel was carrying about 30 people on Table Rock Lake, a popular tourist attraction near the town of Branson, when it capsized, local media say.
Divers have been searching the lake for about five people who are missing.
Seven others were taken to hospital, two of them seriously injured, police said.
Emergency crews said they responded to the incident shortly after 19:00 (00:00 GMT) on Thursday.
A spokeswoman for the Cox Medical Center in Branson, Brandei Clifton, said that four adults and three children had arrived at the hospital shortly after the incident.
It happened as a line of powerful thunderstorms rolled through the American Midwest uprooting trees and downing power lines, resulting in a weather warning.
Video footage shot by a witness on shore showed two duck boats struggling through choppy waters and spray.
One of the boats made it to shore but the other was driven back by the wind and gradually swamped.
Stone County Sheriff Doug Rader said one of his deputies was on board at the time and had helped to 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.”
Are duck boats dangerous?
There are hundreds of so-called duck boats in use around the world. The amphibious vehicles are popular with tourists and have been providing tours for decades.
While duck boats have been involved in a number of fatal accidents over the years, such incidents are relatively rare. In the past two decades, more fatalities have been recorded in connection with golf courses than duck boats, according to US statistics.
However in 2016, a woman died when her motorcycle was struck by a duck boat in Boston, leading to a review of the safety laws around amphibious vehicles.
A year earlier, five students were killed and dozens injured when an amphibious vehicle collided with a bus in Seattle. The NTSB later published a report stating that one of the vehicle’s axles had “sheared off”.
In 2013, a tour operator in the UK had its tours suspended after one of its amphibious vessels caught fire.
But the most serious incident with regard to casualties was in 1999, when a duck boat listed and sank just minutes after entering Lake Hamilton in Arkansas. Thirteen people were killed, including three children, after they became trapped beneath the vehicle’s canopy. The cause was later reported to be “uncontrolled flooding” due to a loose part.
What is a duck boat?
The vehicles used for sightseeing tours, such as the duck boat that sank in Branson, Missouri, are based on a design used during World War Two to transport personnel and supplies over land and water -known as the DUKW.
The DUKW, a six-wheel-drive amphibious truck, was first made in the US in the mid-1940s to deliver people and materials ashore where no port facilities existed.
Some 21,000 DUKWs were produced for use during World War Two. Many served on D-Day and in the Normandy landings, where 40% of supplies that landed on the beaches were carried by DUKWs.
DUKWs remained in service with the British and other armies into the 1970s, and were later adapted for use by tour operators.