The start of summer vacation for a Kentucky teen turned into a nightmare when the girl's legs were severed above the ankle while she was on an amusement park thrill ride on Thursday, park officials said.

The accident happened around 4:45 p.m. on the Superman Tower of Power at Six Flags Kentucky Kingdom, said Six Flags spokeswoman Wendy Goldberg.

Click here to watch FOX 41's report.

A witness, Chris Dinnette, was riding one car over from the girl who was hurt. He told NBC affiliate WAVE he heard what he thought were screams of excitement. But then he saw a cable "come back and hit a lot of people" and realized he was hearing screams of horror.

The girl was taken to University Hospital. There was no immediate word on her condition.

"We were about to ride that ride before it happened," parkgoer Megan Watham told WAVE. But a friend talked her out of it. "She said 'let's not ride it, let's go ride something else.' That could have been all of us."

Click here for the WAVE report.

The ride lifts passengers 177 feet straight up, then drops 154 feet, reaching a speed of 54 mph according to the park's Web site.

The ride has been shut down indefinitely while park officials investigate what caused the accident. The rest of the park remained open.

The Associated Press contributed to this report.