According to La Gazzetta dello Sport, the accident occurred in the vicinity of San Marino.
The Fiat 500 car, in which Mattiuzzo and her boyfriend Daniele Volanti were, drove into the oncoming lane and collided with a Volkswagen Golf.
As a result, Mattiuzzo and Volanti died on the spot, and the Volkswagen driver was injured.
Mattiuzzo, as part of the Italian national team, took part in the 2019 World Junior Synchronized Skating Championships in Switzerland.
Earlier it was reported that 19-year-old motorcycle racer Rene Hofer was killed in an avalanche in Austria.