A football fan has been shot dead by police during a fight between rival supporters in Italy, officials say.
Local authorities said there had been a "tragic error" when police intervened to quell violence between fans of Roman team Lazio and Turin-based Juventus.
The victim, a Lazio fan, was on his way to an Inter Milan-Lazio game when he was shot at a motorway rest stop near the Tuscan city of Arezzo.
Later about 200 armed fans attacked a police barracks in Rome.
The Inter-Lazio game was postponed after the shooting and other matches started 10 minutes late, with players and officials wearing black armbands.
The Juventus fans were reportedly on their way from Naples to an away match against Parma.
"It was a tragic error," said Arezzo police chief Vincenzo Giacobbe.
"Our agent had intervened to prevent the brawl between these two groups, who had not been identified as fans," Mr Giacobbe said, according to the Italian news agency Ansa.
The victim was identified as Gabriele Sandri, a 26-year-old disc jockey from Rome.
He was apparently shot while in a car outside the motorway restaurant.
Police suggested the fan may have been killed by a warning shot.
The exact details of the shooting are unclear and an investigation is underway.
News of the death prompted anger among Italian fans.
In Bergamo, where Atalanta were playing AC Milan, police and fans clashed ahead of the match.
The game was abandoned 10 minutes after kick-off, when fans tried to smash down a barrier and force their way onto the pitch.
Sunday's late match between AS Roma and Cagliari in Rome was also postponed.
A crowd of people wielding rocks and clubs then attacked a police barracks close to Rome's Stadio Olimpico.
Fans smashed windows and burned vehicles outside, then clashed with police.
In April the Italian government introduced a law aimed at stamping out football hooliganism.
It was enacted after a policeman was killed in rioting at a match in Sicily in February. ( BBC )