LOUISVILLE, Ky. -- Six Flags has shut down four thrill rides at parks around the country after a gruesome accident at an amusement park in Louisville, Ky.

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On Thursday, a 13-year-old girl's feet were severed just above the ankles as she rode the Superman Tower of Power ride. The park's Web site said the ride lifts passengers 177 feet straight up, then drops 154 feet.

A Six Flags spokeswoman said the company has shut down similar rides at parks in St. Louis; Gurnee, Ill.; and near Washington, D.C., as a safety precaution.

Investigators have returned to Six Flags Kentucky Kingdom Friday to examine the ride there.

A state spokesman said the cause of an amusement ride accident may never be known.

Bill Clary, of the Kentucky Department of Agriculture, made the comment to The Associated Press Friday. The department inspects amusement park rides in Kentucky.

Dispatchers said they got the call around 5 p.m. Thursday. Officials said both her feet were detached above the ankle.

According to MetroSafe dispatch supervisors, the girl was riding the Superman Tower of Power, which is 177 feet tall and drops riders at 54 mph. According to Kentucky Kingdom, the girl was injured when the ride malfunctioned.

"We seen the cable break loose soon as it got to the top on the right-hand side," said Chris Williams, who witnessed the event.

Treva Smith said it snapped again as the ride descended.

"The people on the ride just came and hit the ground," Smith said.

Williams said she saw the teen maimed.

"As the ride came down, the wire swung left, struck the young lady on the back side of my children," Williams said.

Williams' daughter Amber said she gave up her seat to the 13-year-old and was sitting on the other side of the ride. Williams rushed toward the ride to find his daughter. As Smith raced to find members of her group, she said she made a gruesome discovery.

"When I got up there, the lady, she was just sitting there and she didn't have no legs," Smith said. "She didn't have no legs at all. She was just calm, probably in shock from everything."

Smith said she saw no blood and the girl wasn't crying, but the same couldn't be said for many who witnessed the incident on the ride formerly known as the Hellevator.

"My son's over there tripping out, man," Williams said. "You want to come to a park and feel safe, you know. We've got season passes. We're not coming back for sure."

But other visitors aren't so worried.

"Every park, one in a million, maybe, something happens," park visitor Kenneth Lay said. "But I have no fear."

EMT personnel were on hand to immediately transport the girl to a hospital. As of 10:34 p.m. Thursday there was no word on her condition.

Inspectors arrived Thursday night to begin determining what happened. They said they checked the cable in question.

The ride was shut down and was scheduled to remain so until the investigation has been completed.

A Swiss company called Intamin designed the Superman Tower of Power. Intamin is considered a leader in the design of amusement park rides. It has supplied some two dozen different styles of rides at amusement parks around the world, according to Louisville, Ky., TV station WKLY.

The company is responsible for a number of rides similar to Superman Tower of Power, and is credited with inventing the first free-fall ride.

Related links:

(.PDF) Safety Commission Report On Amusement Ride Injuries