The Italian Football Federation (FIGC) has suspended all matches indefinitely after a policeman was killed at a Serie A match between Catania and Palermo. (BBC).
Officer Filippo Raciti died as violence flared during the Sicilian derby.
The FIGC has called off all this weekend's professional and amateur games, and also cancelled Italy's friendly with Romania on Wednesday.
Commissioner Luca Pancalli said: "What we're witnessing has nothing to do with football, so Italian football is stopping."
According to reports, 38-year-old Raciti was struck in the face by a small explosive while attempting to deal with fighting outside the stadium.
He was taken to hospital but died from his injuries.
Pancalli had warned earlier this week that more violence would bring a halt to league matches after clashes between supporters and police in several cities last Sunday.
"One day is not sufficient," Pancalli added after proceeding with his threat. "Without drastic measures, we cannot play again.
"We will immediately set up a commission to discuss the situation between sport and politics. It's not possible to carry on like this."
Catania, fifth in Serie A, against Palermo, who are third, was given an early kick-off time on Friday because of fears over public safety.
Prior to the start, a minute's silence had been held following the death of a club official from lower league club Sammartinese last weekend.
But the match was suspended after an hour when tear gas, used by police to break up the fighting outside the ground, drifted onto the field.
The fighting, reported ANSA news agency, was because Palermo fans could not get into Catania's Stadio Massimino until the second half.
The two teams fled the pitch for the dressing-room, with the game suspended for 30 minutes.
After the match, fans continued to fight running battles with police on the streets outside the stadium and around a hundred people were treated for injuries, while dozens with lesser injuries were taken to local hospitals.
Another police officer is also believed to be in a critical condition.