Multiple riders sustained broken bones from the ride, which is located in Japan’s Fuji-Q Highland Park. The rollercoaster is known for its “super death” speed. The ride is heavily regarded as the world’s fastest-accelerating design with its ability to go from zero to 112 miles per hour in just 1.56 seconds.

Specifically, Newsweek recently noted that “four people have broken bones” while Vice World News cites that at least six riders have bone fractures and four of them were injuries to the back and neck. Further details of the injuries have pointed out that those who sustained injuries were in their 30s to 50s. For full recovery, the neck and back injuries could take up to three months.

Naoya Miyasato, an architecture professor at Nihon University, believes the problem stems from the ride’s literally breakneck acceleration. The ride’s acceleration is similar to that experienced by astronauts during rocket launches. However, these injuries are relatively recent. Miyasato says it could be due to how riders sit. “If someone is sitting incorrectly, such as with too much space between their backs, and their seat, then it is the responsibility of park employees to verify their seating position.”