Masked rioters smashed shop windows and looted stores in Frankfurt late on Saturday as Germany's cost-of-living protests, largely peaceful during the day, turned violent after dark in Berlin, Cologne and Hamburg.

Police said special units were deployed in Frankfurt city centre, where a large section of the main shopping street was closed off. Windows of several shops were broken, Molotov cocktails were thrown at emergency services and looters stole trainers and other goods, according to police and local media. A gun shop's windows were smashed and two weapons were seized after a suspect was arrested.

The demonstrations were organised by a youth campaign called Gen Z regelt — roughly "Gen Z takes charge" — which rallied in more than 30 cities for education, health, climate protection and affordable living, and against any return of military conscription.

A day that split in two

Earlier in the day, thousands joined largely peaceful marches. By nightfall, groups of protesters refused to disperse and clashes spread.

Frankfurt police said "violent riots" were occurring in the city centre. In Cologne, officers were attacked near the main railway station with bottles and a bicycle, and in Hamburg people dressed in black set off fireworks and burned barricades, with public broadcaster NDR reporting 120 arrests.

Berlin police said a smaller evening demonstration left 27 officers injured and up to 56 people temporarily detained.

Authorities in Frankfurt, Munich and Berlin reported as many as 18,000 protesters — roughly half the number the organisers had estimated on their website. German media reported tens of thousands demonstrating across the country on Saturday. Organizers said that tens of thousands participated in the protests across the country, but official figures were not immediately available.

"Infected by extremists"

Roman Poseck, interior minister of Hesse, the state that includes Frankfurt, said around 100 "clearly identified left-wing extremists" had infiltrated the protest, and called the way it ended "shameful".

"We all have those images from France in our minds — looting, burning houses, burning police vehicles, and attacks on police officers," he said. "France must not be held up as a model in this regard."

Cologne's police chief, Johannes Hermanns, said it was "deeply saddening that young people who wanted to peacefully demonstrate for their future were infiltrated today by extremists who had nothing but violence in mind".

Organisers denied they had called for confrontation. Gen Z regelt spokesperson Lina Friedrich said the demonstrations were "to fight for peace and freedom, rather than for war and coercion". "What matters most to us is better support for the health and education systems," she said. "We are against compulsory military service and we are in favour of a fairer distribution of the burden."

One weekend, many countries

Germany was not alone. In France, more than 320,000 people took part in a third consecutive weekend of largely peaceful protests over the cost of living and public services, and officers fired tear gas in some cities. More than 500 arrests followed clashes in Toulouse, Lyon and Marseille, and French interior minister Laurent Nuñez said a police officer had been injured by a Molotov cocktail.

Police in Paris said several hundred rioters had attacked security forces with projectiles.

There were also clashes between police and demonstrators in Rome and Turin, and in Portugal police moved to clear a tent camp set up after thousands marched against a rental bill they say could worsen the housing crisis.

Mostly young protesters have taken to the streets in France, Belgium, Ireland, Spain, Portugal, Italy, Greece, Serbia and Albania in recent weeks. The demands differ from country to country, but the common thread is the cost of housing, education and everyday life.

What the violence costs

The clashes hand governments an argument they have been looking for. In both France and Germany, ministers have pointed to a violent fringe to frame the wider movement as a security problem rather than a social one — and the imagery from Frankfurt on Saturday night will make that easier.

They also complicate the movement's own message. Gen Z regelt has built its appeal on being conspicuously peaceful, with marches led by students and families; scenes of looting in a financial district give opponents a shorthand for dismissing the whole.

The immediate question is whether the violence stays confined to a fringe. Police said the situation in Frankfurt calmed overnight into Sunday, but further demonstrations have been called, and the German interior ministry has not announced any change of approach.

The broader one is whether European governments can answer the economic complaint behind the marches. The demonstrations have been framed by organisers as demands about schools, rents and public services; the response so far has been police deployment and condemnation of extremists.

For now, both sides are describing different events. Ministers see a security problem; organisers see a generation priced out of the basics. The weekend's images will not settle that argument — but they will shape how it is reported.

Similar unrest has already reshaped politics elsewhere on the continent: the European protest wave has fed into France's presidential contest, while inflation and squeezed household budgets remain the backdrop across the West.