Officials say several boats sank on a lake in the US state of Texas during a parade in support of President Donald Trump in the November election.
Officials say the choppy water may have been caused by a large number of ships floating together near Lake Travis, near the state capital, Austin.
Pictures of Trump campaign flags being flown at nearby quarters.
The media said people were to be rescued from the water, but there were no immediate reports of injuries.
The event, called the Lake Travis Trump Boat Parade, was held on Facebook, and more than 2,600 people marked themselves by participating.
Kristen Dark, a spokeswoman for the Travis County Sheriff’s Office, said an investigation had been launched and there was no evidence of any deliberate act.
“We were saddened by the response to several calls from boats, many of which sank,” he said. “We had unique boats on the lake today … when they all started moving at the same time, it made significant waves.”
The incident took place on Saturday, Labor Day weekend in the United States at 12:00 noon (17:00 GMT). The incident page said the boats were told to drive at 10mph (16km / h).
Paul Yurara from the National Weather Service in Austin / San Antonio told the Associated Press that there were no storms in the area at the time of the parade.