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TOKYO, May 5 (Reuters) - A rollercoaster went off the rails and crashed into a balustrade at a theme park in the Japanese city of Osaka on Saturday, killing a woman and injuring 21.

The six-coach switchback was carrying two dozen "Golden Week" holidaymakers, a police officer said.

The cause of the accident was not immediately known, he said.

The operators of the theme park said their self-imposed regulations set the rollercoaster's speed limit at 75 km per hour (47 miles per hour) on the 40-metre-high (130 feet) track.

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