TOKYO, May 5 (Xinhua) -- A woman died and 21 people were injured, one seriously on Saturday after a roller coaster derailed in a park in Osaka prefecture.

    The accident occurred at around 12:50 a.m. local time (0350 GMT) in amusement park "Expoland" in Suita, Osaka prefecture when the roller coaster derailed and hit a steel bar alongside the rail, killing the woman instantly, Kyodo News reported.

    One person sustained serious injuries and the remaining 20 suffered minor injuries.

    The accident was caused by the sudden breaking of an axle of the stand-up roller coaster, officials of the park told a press conference. The roller coaster was carrying its maxim 24 passengers when the accident happened. It can run at a speed up to75 kilometers per hour and reach up to 40 meters above the ground.

    According to reports, the broken axle, five centimeters in diameter, has not been replaced since the attraction was installed at the park some 15 years ago.

    The park was closed after the accident, which occurred in the last day of Japan's Golden Week holidays.

    Following the fatal accident, the Land, Infrastructure and Transport Ministry ordered operators of similar amusement establishments across the nation to conduct immediate checks.

    The Osaka police have also set up an investigation team on suspicion of negligence by the park operators, Kyodo reported.