The Italian league was thrown into chaos yesterday following the fatal shooting of a Lazio fan, Gabriele Sandri, who was 26 years old.
Sandri, a disc jockey, was shot at a motorway service station near Arezzo as police attempted to intervene to quell trouble and a police spokesman all but confirmed media reports that the fatal bullet came from a police weapon.
As news broke of the shooting, the reverberations were felt elsewhere even though the Italian football authorities, as well as calling off Lazio's game with Internazionale in Milan, at first ordered that the remaining matches kick off 10 minutes later as a mark of respect to Sandri.
Fighting marred the build-up to the Atalanta-Milan game and then the referee, Massimiliano Saccani, took the teams back to the changing rooms after seven minutes of play when Atalanta fans attempted to invade the pitch. The official decided after a 25-minute wait to call off the game.
The Milan defender Alessandro Nesta, a member of Italy's World Cup-winning squad, said: "We all came out ready to play. Unfortunately, certain episodes happened with Atalanta fans trying to provoke the suspension of the game. But the problem is not inside the stadiums. The problem is that what happens inside the stadiums is a reflection of our society."
Roma's evening match with Cagliari was called off after the Eternal City club asked for it to be put back out of respect for Sandri, but an angry mob turned up at the Stadio Olimpico.
Hundreds of them, armed with stones and sticks, attacked one of the police units in the vicinity of the stadium before raiding the headquarters of the Italian Olympic Committee, CONI, in Rome. The CONI security guards, who were unarmed, had to barricade themselves inside the building while waiting for back-up.
The incidents come nine months after a policeman, Filippo Raciti, was killed at the Sicilian derby between Catania and Palermo during crowd trouble outside the stadium.
That led to the Italian government severely tightening security with numerous stadiums closed until they made improvements. The government also created an independent body, L'Osservatorio nazionale sulle manifestazione sportive, to clamp down on football violence and gave it powers to call games off or ban fans from attending.
Vincenzo Giacobbe, the head of police at Arezzo where the shooting took place yesterday, confirmed that a man had died and did not deny media reports that the fatal bullet had come from a police weapon.
"This is a tragic mistake," he said. "Our agent had intervened to prevent the fracas between two groups of people – that had not been considered fans – degenerating into a situation with serious consequences for both groups. I express my most profound pain and sincere condolences to the victim's family."
Forensic tests are to be carried out to ascertain whether the bullet had been fired by a police officer. The police made it clear that this was not, in fact, certain.
The Italian Prime Minister, Romano Prodi, expressed his shock over yesterday's events. Prodi was in church when a government aide informed him of the shooting. Prodi said: "These are episodes that increase concern. I was made aware of the situation by the Minister of Interior while I was at mass."
A Lazio spokesman, Giacomo Mazzocchi, said of the incident: "It's shocking and inexplicable. We are still asking ourselves how could something like this have happened. It's a tragedy."
The president of the Italian football federation, Giancarlo Abete, had initially ruled that all games bar the Internazionale-Lazio match should go ahead.
Speaking before the abandonment of the Atalanta-Milan game and ahead of the decision to postpone the evening match between Roma and Cagliari, Abete said: "I would be intellectually dishonest if I said that we had not considered postponing all of today's games. But we believe that we have taken the right decision. The incident has yet to be clarified and it should not create any animosity between the fans and the police because what has happened is not yet clear."
Roma's later request to call off their game against Cagliari was eventually approved with Lazio's city rivals determined not to aggravate already high feelings with their co-tenants at the Olympic stadium.
The club's managing director, Rosella Sensi, said: "It is right to ask for the game to be postponed as a sign of solidarity for the Lazio fans and for the city of Roma hit by the death of Gabriele Sandri."