At least one fan and one police officer are reported to have been shot before the Italian Cup final between Napoli and Fiorentina.
The fan is said to be in a serious condition.
The Ansa news agency said the shootings happened in an area where Napoli supporters were gathering for the match.
The fan was reportedly shot in the chest, while the police officer was shot in the hand.
The circumstances of the shootings were not immediately clear.
The match at the Stadio Olimpico was scheduled to begin at 3pm local time.
Disturbances were also reported outside the stadium.
