Simplify the following text for a Grade 8 native English-speaking person.
Original: The disaster at the 24 Hours of Le Mans on 11 June which killed Mercedes sportscar driver Pierre Levegh and over 80 spectators led to the cancellations of the French , German , Spanish and Swiss Grands Prix .
Simplified: A terrible crash at the 1955 24 Hours of Le Mans on June 11 killed Mercedes driver Pierre Levegh and over 80 spectators . This crash led to the cancellations of the French , German , Spanish and Swiss Grands Prix that year .