Serious clashes broke out in the center of Naples between Eintracht Frankfurt fans and police ahead of the German team's Champions League match against Napoli on Wednesday.
Car windows were broken and fans hurled flares, chairs and other objects as innocent bystanders took shelter in bars and restaurants. A police car and other vehicles were set on fire.
Police in riot gear eventually managed to calm the situation, shepherding the fans onto buses to take them to their hotels.
Further clashes were avoided as the majority of Napoli "ultras" were stopped from coming into contact with the German fans. They did throw stones and bottles at the buses, however.
The Serie A leaders went on to win the match against Frankfurt 3-0 to advance 5-0 on aggregate to the quarterfinals of the Champions League.
Police had been on high alert in the Italian city -- around 800 officers had been deployed -- as more than 600 people arrived from Germany despite Frankfurt forgoing their allocation of tickets for the round-of-16, second-leg match in protest. That number was boosted further by Atalanta "ultras," who have a bitter rivalry with Napoli.
"These are not fans, they are criminals, thugs. I wonder if they would make the same mess in Germany?" Italy's Deputy Prime Minister Matteo Salvini wrote on Instagram, while expressing his "full support" for police on the ground.
Fans of both teams clashed prior to the first leg in Frankfurt with police having labelled the game as high risk.
The German club was objecting to a decision by local authorities in Naples banning any fans who are residents of Frankfurt from buying tickets, following unrest between supporters during the first leg in Germany.
Napoli won that match 2-0 but local police made several arrests in the buildup amid altercations between fans.
Information from the Associated Press and Reuters was used in this story.