The Theme Park Ride Where 4 People Died in Australia Is Also Popular in the U.S.

Some of the biggest amusement parks in the U.S. boast river rapids rides similar to the popular water attraction in Australia where four people died on Tuesday.

Two women and two men, between the ages of 32 and 42, died on the Thunder River Rapids ride in Dreamworld in Queensland after a malfunction caused two of the passengers to be thrown from their raft while another two were stuck inside of it, authorities said.

It’s unclear what caused the accident, which is under investigation. Queensland police said in a statement that they were called to the water park about 2:20 p.m. following reports that people were “injured by a conveyor belt.” Photos of the accident scene show an overturned raft on the track.

Dreamworld, which is closed until further notice, said it was “deeply shocked and saddened by the incident.” On its website, Thunder River Rapids is described as relatively tame ride with “moderate thrills.” It simulates whitewater rafting, with riders traveling at up to about 28 mph down a man-made river.

Similar rides—in which multiple people are strapped into a circular raft that bounces around on water, often on a track—are offered at major attractions in the U.S. like Disney World in Florida and several Six Flags locations.

Popeye and Bluto’s Bilge Rat Barges in Florida’s Islands of Adventure theme park, Roaring Rapids in Chicago’s Six Flags Great America and the Kali River Rapids at Disney’s Animal Kingdom all promise a water-soaked adventure for thrill-seekers. Six Flags said its rides are from a different manufacturer, adding that “the safety of our guests is always our top priority and our water rides will undergo a thorough inspection prior to opening.” Disney did not immediately comment.

More than 85 million people safely enjoy water park attractions in the U.S. each year, according to the International Association of Amusement Parks and Attractions, which said fatal injuries are “extremely rare.”

Earlier this year, safety advocates urged for more federal oversight after a 10-year-old Kansas boy was decapitated on the world’s tallest water slide.

It’s unclear when Dreamworld’s Thunder River Rapids was last inspected and how long it has been in operation. In a statement on Wednesday, Dreamworld said the park was fully certified and that there has never been a death in the park prior to the four people killed on Tuesday.