Rioters looted shops in central Frankfurt late Saturday, and clashes with police broke out there and in Berlin, Cologne and Hamburg after largely peaceful mass demonstrations, BBC Business reported.

Police said they used water cannon to disperse protesters who threw fireworks, stones and bottles at emergency workers. In Frankfurt, police reported smashed shop windows and Molotov cocktails thrown at emergency services.

A large stretch of Frankfurt’s main shopping street was cordoned off, according to AFP, cited by the BBC. A police spokesperson said many arrests had been made. Officials later said a gun shop’s windows had been smashed and two weapons seized after a suspect was arrested.

Thousands had joined daytime protests organised by Gen Z regelt, a campaign group whose name means “Gen Z takes charge”. The demonstrations opposed school underfunding, high living costs, public spending cuts and military service. Authorities in Frankfurt, Munich and Berlin reported up to 18,000 demonstrators—roughly half the organisers’ estimate.

Lina Friedrich, a spokesperson for the group, said its priorities included stronger health and education services, opposition to compulsory military service and a fairer sharing of financial burdens.

Roman Poseck, interior minister of Hesse, the state that includes Frankfurt, said around 100 people he described as left-wing extremists had infiltrated the city’s protest. He condemned the violence and called the way the demonstrations ended shameful.