The Italian newspaper La Repubblica has compared the scenes to "urban warfare". The violence is believed to have taken place at the Drunken Ship pub - images on La Repubblica's website appear to reveal the damage.
The Lazio fans were reportedly armed with knives, baseball bats, belts and knuckle dusters and they went on to "destroy" the venue. One witness told the paper: "We feared the worst."
More top news
UK airport passengers have to walk up to a kilometer from check-in desks to reach their departure gates, new research has shown.
In an annual survey taken among local authorities in the UK, 2,463 stray dogs were put to sleep between April 2015 and March 2016.
Inspectors found the availability of drugs at HMP Bedford was having a "serious impact" on safety.