The 26-year-old son of an alleged mafia boss was shot dead and more than a hundred people were injured on Thursday during delirious celebrations by football fans in Naples, after the city’s team won its first Serie A title in 33 years. Vincenzo Costanzo, who was known to police and had a “significant” criminal record, was gunned down during the spontaneous street partying that took place across the city after Napoli were crowned champions. He was the son of Maurizio Costanzo, described by investigators as a leading member of the Neapolitan mafia in Ponticelli, where a feud among clans is ongoing. During the incident, three other people were injured. According to police, Costanzo died in hospital as a result of gunshot wounds. Prosecutors and Carabinieri police in Naples are investigating whether he was intentionally killed by a rival clan or if the gunshots were accidental. In numerous cities in southern Italy, it is not uncommon for people to celebrate by firing shots into the air. Tens of thousands of fans celebrated through the night after a 1-1 draw against Udinese secured the title, many waving flags featuring the image of the late Diego Maradona, who was Napoli’s star player when the city won its last Scudetto in 1990. More than a hundred people were taken to hospital, including people with hand and arm injuries from fireworks, knife wounds and injuries from numerous brawls. A 20-year-old woman was in critical condition after she was hit by a car during the celebrations in Frattamaggiore in the province of Naples. Three police officers also suffered minor injuries. The prefect of Naples, Claudio Palomba, told la Gazzetta dello Sport that “the security plan, developed to prevent the celebrations from degenerating, worked”, and added that police checks and surveillance of the streets “will also continue next Sunday, when Napoli returns to the field against Fiorentina”. Palomba said the killing was not connected to the celebrations. The Naples mayor, Gaetano Manfredi, repeated that claim on Friday to Radio Anch’io. He said: “This death is related to dynamics that have nothing to do with the celebrations… It was probably a settling of scores that took advantage of the party.” Preparations for the party got under way in early March, as Napoli climbed the division. Neighbourhoods across the city ploughed their own money into decorations, saturating the streets with flags and banners in their team’s blue and white colours. Tattoo artists have done a roaring trade as fans poured into their studios to mark the occasion. Napoli had hoped to claim the glory of the Scudetto, with six games still to play, last Sunday, but a 1-1 draw against Salernitana meant it had to delay the official party by a few days. Already last week, the city authorities, worried about the consequences of the celebrations, deployed thousands of police in the streets. Even the US consulate issued a security alert, saying “spontaneous celebrations could last multiple days”, and warned of “heavy traffic or road closures, significant use of fireworks, and alcohol consumption, throughout the city”. Cars and scooters were also banned by authorities in the hope of minimising risk to public order. This is the third Italian championship won by Naples and the first time a club south of Italy’s traditional football capitals of Milan and Turin has won the league since Roma claimed the title in 2001. Napoli led the table for most of the season, having lost only three games and producing some of the most entertaining football in Europe, spearheaded by the Nigerian striker Victor Osimhen and the Georgian winger Khvicha Kvaratskhelia, both of whom have become local legends. Celebrations erupted on Thursday evening when the equaliser against Udinese was scored, 12 minutes after half-time by Osimhen, who joined from Lille in a club record €70m deal. Napoli played away from home, in Udine, but more than 50,000 supporters converged on the Diego Armando Maradona Stadium in Naples, where the match was shown on big screens. “This is the coronation of a dream that’s been going on for 33 years,” Napoli’s president, Aurelio De Laurentiis, told the crowd on Thursday. “It’s been a long process.” “Napoli, this is for you,” the team’s coach, Luciano Spalletti, said. “There are people here who will be able to get through difficult moments in their lives because they remember this moment. These people deserve all the joy.”