Frankfurt in flames

... and not just around the new European Central Bank (ECB) headquarters. Police cars in the city center were also set on fire. Because of the riots, the fire brigade couldn't deal with the fires properly.

Fourteen police officers and 21 anti-capitalist protesters were wounded in the first street battles in the early hours in the well-heeled western city of Frankfurt. Police initially arrested 19 people.

Even from a distance, observers saw an "unusual day" in Germany's financial capital.

Seven police cars were set on fire, streets were blocked by burning stacks of tyres and rubbish bins, and shops were damaged in the city center. Protesters threw stones at police officers, firefighters and trams.

Activists from Blockupy (an alliance of about 90 groups who organized the protest) condemned the violence in Frankfurt, but also the force police used against protesters.

Many police officers and demonstrators were injured in the clashes - but also as a result of police using tear gas and water cannon.

Police arrested a total of about 350 demonstrators in the protest planned to coincide with the inauguration of the ECB's new 1.3-billion-euro ($1.4-billion) headquarters. The police union said it was the worst violence against police seen in Frankfurt in a long time.

A march through the city center and rally on Frankfurt's historic Römerberg square in the afternoon drew 15,000 people, according to police, though organisers put the number at 20,000.

The leaders of Blockupy distanced themselves from the violent rampage that engulfed the skyline in smoke. "That was not what we had planned or agreed to," Blockupy spokesman Ulrich Wilken said.

The wave of violence resulted in Frankfurt authorities shutting down some transport services and cleared the inner city of a large amount of private road traffic. Many ECB employees worked from home while some schools ended classes early.

The new ECB headquarters in Frankfurt's Ostend district has 2,900 employees. It was completed in 2014.