BRUSSELS, April 30 (Xinhua) -- A number of spectators were injured, some seriously, when a racing car ploughed into the crowd watching the Queen's Day pageant in a central Dutch city on Thursday.

    The car, which took part in the pageant in Apeldoorn, hit a number of spectators with high speed and threw them into the air, Radio Netherlands reported.

    An unknown number of spectators were injured, some seriously, the report said.

    The incident occurred minutes after a luxury coach carrying the Dutch royal family passed the spot.

    Emergency services were rushing to the spot.

    Queen's Day is a Dutch national holiday which celebrates the birthday of the Dutch Queen.

    The tradition started on Aug. 31, 1885 on the birthday of Princess Wilhelmina, later Queen Wilhelmina.

    Since 1949, after the ascension of Queen Juliana, Queen's Day is Queen Juliana's birthday on April 30.

    When Queen Beatrix ascended the throne in 1980, she kept the holiday on April 30 as a tribute to her mother.

    This year's Queen's Day marks the 100th anniversary of the birth of the late Queen Mother Juliana.