TORONTO (Reuters) - About 1,500 Americans floating down a river that separates the United States from Canada had to be rescued from the water when strong rains and winds sent them illegally into Canadian territory, the country’s coast guard said on Monday.

A Canadian Coast Guard ship tows floatation devices used by U.S. partiers to the Canadian side of the St. Clair River between Michigan and Ontario on August 21, 2016. Canadian Coast Guard/Handout via Reuters

The Americans were taking part in the annual Port Huron Float Down on Sunday in the St. Clair River, which runs between the U.S. state of Michigan and the Canadian province of Ontario.

The winds blew the flotilla of inflatable rafts and inner tubes off course and toward the Canadian shore. Some rafts deflated, spurring a rescue effort by the Canadian Coast Guard as well as federal and provincial police, coast guard spokeswoman Carol Launderville said in an email.

Most “floaters” had to be rescued from the water, with many towed to shore, according to the coast guard.

“They were terrified of entering another country without documentation. No one carries their passport or any ID, and a lot were drinking alcohol,” Peter Garapick, superintendent of search and rescue for the coast guard, told CBC television.

Some tried to swim back to the United States.

“We had to pull a lot of people out of the water and say ‘no,’” Garapick said.

The Americans were gathered at Sarnia, Ontario, and bussed back to the United States by the city’s public transit.

Sarnia police did not say whether anyone was charged in the incident and there were only minor injuries reported.

Launderville said the event has no official organizer and poses “significant and unusual hazards” due to the river’s fast-moving current and participants’ lack of life jackets.

A Facebook page for the event, which dates back more than 30 years in the city of Port Huron, west of the border from Sarnia, made a post Sunday night thanking Canadian authorities.

“You’ve shown us true kindness and what it means to be amazing neighbors!” the post read.

The Facebook page appears to be operated by a group named Port Huron Float Down, which says on its website it is not an organizer. The page’s operators did not immediately respond to a request for comment.