Violent rioting erupted during youth-led cost-of-living protests in Germany, with rioters smashing shop windows and looting stores in Frankfurt. German authorities in Frankfurt, Munich and Berlin reported up to 18,000 protesters, about half the organisers' estimate, as demonstrations in several cities turned destructive late on Saturday. Earlier that day, thousands joined largely peaceful marches organised by a campaign group protesting underfunding in schools, the high cost of living, public spending cuts and military service. In Frankfurt, police said “violent riots” were under way in the city centre. Shop windows were smashed and Molotov cocktails were thrown at emergency services. Rioters broke into shops and stole items including trainers, and they smashed the windows of a gun shop. Police arrested a suspect and seized two weapons. A large section of the main shopping street was closed overnight, and many arrests were made. Cologne police chief Johannes Hermanns said young people who wanted to demonstrate peacefully were “infiltrated” by extremists determined to use violence. In Cologne, officers were attacked near the main train station, with bottles thrown and a bicycle launched at them. In Berlin, a smaller evening demonstration left 27 police officers injured, and police temporarily detained up to 56 people. In Hamburg, people dressed in black set off fireworks and set barricades on fire, and public broadcaster NDR reported 120 arrests. Police used water cannons to disperse protesters who targeted emergency workers with fireworks, stones and bottles. Roman Poseck, interior minister of Hesse state, said around 100 clearly identified left-wing extremists had infiltrated the protest in Frankfurt, calling it “shameful” that it ended in violence. At least one suspect was arrested and two weapons were seized in Frankfurt, as police continued dealing with the unrest.