A Missouri couple says they found themselves in a life-or-death moment on a roller coaster after a young girl’s seat belt allegedly came undone mid-ride.

Chris and Cassie Evans were riding the Mamba at Worlds of Fun in Kansas City on October 11 when they heard a sound they’ll never forget — a scream that didn’t sound like excitement. “The girl sitting behind my wife just lets out this blood-curdling scream like I’ve never heard before,” Chris told Fox 8. “I assumed it was her first time on the ride, but then she said her seat belt came undone.”

The Mamba, the park’s tallest roller coaster, drops 205 feet at speeds topping 75 miles per hour. The Evanses, who know the ride well as season ticket holders, immediately realized the danger. “I looped my arm underneath her lap bar,” Chris said, describing how he braced the girl as the coaster climbed and plunged through its track. “There was a huge space, no seat belt. I grabbed her wrist. My wife was pushing down on her legs.” Every turn became a fight against gravity. “As we crested each hill, I could feel her lifting out of her seat,” Chris recalled. “So I shifted to push down on her whole body to keep her from coming out of the seat.”

When the train finally rolled back into the station, they reported the incident to park management. The couple says they never saw the girl again but hope she’s okay. Worlds of Fun confirmed that the Mamba was shut down immediately after the report and inspected before reopening later that day. “The ride is equipped with a multi-layered restraint system, with the lap bar being the primary restraint. It was found to be fully functioning in multiple inspections.”

The park said it also conducted a “comprehensive safety review” and implemented modifications requested by the fire marshal. “Guest and team member safety is a top priority,” the spokesperson added. Cassie, a mother of four, told ABC 7 she hasn’t been able to stop thinking about the moment. “The scream that she screamed — I had never heard anything like that before in my entire life,” she said, her voice breaking. “It was terrifying.” For the Evans family, the ordeal changed how they see the park they once loved. “We probably won’t go back for a while,” Cassie said. “We need to see a change. Once we see that change, I’ll be comfortable taking my four children there. But not right now.”