(CNN) -- An Italian police officer was under investigation Monday over the accidental fatal shooting of a football fan over the weekend which threw Italian football into a fresh crisis.

Football supporters demonstrate after the match between Inter Milan and Lazio was cancelled.
"What a nightmare!" said the front page of Italy's Gazzetta dello Sport newspaper, reflecting on a weekend in which three Serie A matches were cancelled or abandoned and supporters rioted in Rome and elsewhere in apparent protest over the death.
Gabriele Sandri, a 26-year-old Lazio fan and a Rome-based DJ, was shot in the neck Sunday as he sat in a car at an autoroute rest area near the Tuscan town of Arezzo while traveling from Rome to Milan for his side's Serie A clash with Inter Milan.
Local police said the incident occurred as officers fired shots to break-up an apparent scuffle between rival fans -- understood to be supporters of Lazio and Juventus.
"I express deep sorrow and sincere condolences to the family of the victim," Arezzo police chief Vincenzo Giacobbe said, describing the incident as a "tragic error," the Associated Press reported.
News agency ANSA, citing police sources, said the policeman who fired the shot had been placed under investigation for possible manslaughter by magistrates in Arezzo.
A police statement on Sunday claimed the officers had fired two shots into the air from the opposite side of the highway. But an unidentified police source told the Corriere della Sera newspaper that the second shot had gone off accidentally, AP reported.
Later on Sunday, hundreds of fans in Rome attacked a police station close to the Olympic Stadium, home to both of the city's Serie A clubs, Lazio and Roma, hurling rocks at police cars and setting one on fire, AP said. The nearby Italian Olympic Committee headquarters also suffered damage.
The ANSA news agency reported that at least 40 police officers were injured near the Rome stadium. Police said Monday they had picked up four people accused of taking part in the riots.
Both Lazio's match at Inter Milan and Roma's evening match with Cagliari were cancelled.
Meanwhile, AC Milan's game with Atalanta in Bergamo was stopped after seven minutes as fans tried to break down a glass barrier separating them from the pitch. Other matches kicked off 10 minutes late with players and referees wearing black armbands.
Sunday's violence occurred despite the adoption of stricter security measures at football matches -- with some fans barred from traveling to their teams' away games -- after a Sicilian police officer died and around 100 people were injured in February during clashes between rival fans ahead of a derby match between Serie A rivals Catania and Palermo.
That incident prompted a crisis in Italian football with all matches postponed for a week and many clubs subsequently forced to play behind closed doors when the season resumed as new security checks were introduced.
Italian football federation president Giancarlo Abete said he had summoned a meeting for Monday to discuss fresh measures to tackle football violence.
"It is another very sad and painful day for all of Italian football," Abete said in a statement. "The first thought is of huge condolences for the family of Gabriele Sandri."
Speaking to RAI state radio, Abete said there was no "miraculous solution" to football violence, AP reported.
"There is sadness and bitterness, but football remains to me something that can offer joy and renew hope, like we saw in Berlin in July 2006," he said, referring to Italy's World Cup victory last year.
"I can't even contemplate a world of soccer within 10 to 15 years made up only of people who (watch games) on TV. I don't even want to think about it."

Italian Prime Minister Romano Prodi called fan violence "very worrisome" while Italian President said he was "very worried" by Sandri's death.
Despite continued success on the field -- the national side's World Cup victory was the country's fourth overall while AC Milan are the current European champions -- Italian football has long struggled to curb a violent subculture, with many top clubs drawing loyal support among notorious groups of hardcore fans known as "ultras." E-mail to a friend ![]()
Copyright 2007 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.

| Most Viewed | Most Emailed |
| Most Viewed | Most Emailed |