Several boats have sunk on a lake in the US state of Texas during a parade to support President Donald Trump in November’s election, officials say.

Authorities say the choppy water was likely caused by the large number of vessels moving closely together on Lake Travis, near the state capital, Austin.

Images showed boats with Trump campaign flags manoeuvring at close quarters.

Media say people had to be rescued from the water, but there were no immediate reports of injuries. 

The event, called Lake Travis Trump Boat Parade, was organised on Facebook, and more than 2,600 people marked themselves as having attended it.

An investigation has been launched and there is no evidence of any intentional act, Travis County Sheriff’s Office spokeswoman Kristen Dark said.

“We responded to multiple calls of boats in distress, several of them sank,” she said. “We had an exceptional number of boats on the lake today… When they all started moving at the same time, it generated significant waves.”

The incident happened around 12:00 (17:00 GMT) on Saturday, Labor Day weekend in the US. The event page said boats were asked to drive at 10mph (16km/h).

Paul Yura, 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.