(CNN) — Americans love roller coasters — until something goes wrong.

Attention turned to amusement park safety after a tree branch that fell on the tracks derailed a roller coaster car at a Six Flags amusement park Monday evening, leaving it dangling precariously and its occupants stranded for hours.

Four people were injured on the Ninja ride at Six Flags Magic Mountain, the Los Angeles County Fire Department said. Two of the four were taken to a hospital as a precautionary measure.

It was an amusement park enthusiast’s nightmare. “It was just a lot of leaf noise and then cracking noises and crashing noises and a lot of screaming,” Brandy Chambers, who witnessed the incident from her vantage point on another ride, told CNN affiliate KTLA.

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