Protests took place across Italy on Monday over new restrictions to curb the country's second wave of Covid.
Clashes were reported in the northern cities of Milan and Turin, where petrol bombs were thrown at officers.
In Milan tear gas was used to disperse protesters, and thousands of people gathered in the centre of Naples.
The demonstrations began soon after the national government's order to close restaurants, bars, gyms and cinemas came into effect at 18:00 local time.
Many regions have also imposed night-time curfews - including Lombardy, where Milan is, and Piedmont, where Turin is. The violence was blamed on extremist agitators and police said 28 people had been arrested in Milan alone.
In Milan, crowds chanted "Freedom, freedom, freedom!" as they clashed with police in the city centre. The city is the capital of Lombardy, which has been particularly hard hit by the virus.
Restaurants, bars and cafes must stop table service at 18:00 and offer only take-away until midnight. Contact sports are prohibited but shops and most businesses will remain open.
Protests took place in about a dozen other cities, including Rome, Genoa, Palermo and Trieste. Taxi drivers occupied a central square in Turin while restaurant owners beat pots and pans in the centre of Cremona.
In Naples, a big crowd gathered in the central Piazza del Plebiscito, many calling on the regional governor to resign.
While an initial national lockdown earlier this year was complied with little resistance, the announcement of renewed measures has been met with immediate pushback.
Small businesses argue that they are still recovering from that first lockdown, and that more restrictions could bankrupt them.