FRANKFURT – Police vehicles burning in the streets, helicopters circling above, cobblestones ripped from pavements and used as missiles, tossed garbage containers, and the smell of smoke and burning rubber pervading the air.

In scenes resembling a war zone, commuters in Frankfurt were greeted with a trail of destruction running through the euro area's financial capital on Wednesday as thousands of demonstrators descended on the city to protest austerity measures and European Central Bank policy.

Frustration over near-record unemployment, a struggling economy and a crisis-management strategy seen as privileging private wealth over poverty alleviation erupted into clashes at the ECB's new headquarters in Frankfurt's east end. Before President Mario Draghi officially inaugurated the $1.4 billion tower, members of the Governing Council were flown in by helicopter, over barbed-wire police cordons, or ferried across the River Main by boat.

"The reason we've called this protest is because the policies of the ECB contribute to an increase in poverty in Europe, splintering society even further," said Thomas Occupy, a spokesman for the protest organizer Blockupy. "The ECB doesn't undertake policy for the whole society."

Nine days after the ECB started its 1.1 trillion euro bond-buying program aimed at reviving the economy across the 19-nation euro area, protesters are laying the blame for recession and unemployment at the doors of Draghi and German Chancellor Angela Merkel.

While the morning's turmoil later calmed, around 10,000 people had gathered by midafternoon at the day's main demonstration on the Roemerberg, Frankfurt's medieval town square, according to an estimate published on police Twitter feed.

From early morning, demonstrators gathered at multiple points across the city, which has a reputation for being staid and conservative. Protesters scaled the Skyper Tower, one of the newest additions to Frankfurt's skyline, to hang a banner with the slogan "Capitalism kills" in the city's financial district.

Martin Dolzer, a member of the Left party from Hamburg, said tear-gas cartridges had been fired from behind police lines. Claudia Rogalski, a police spokeswoman said police only had pepper spray to be used in self-defense.

While nonviolent protesters — such as a group dressed as clowns that had come from France — gathered around the bridge, black-clad rebels levered up cobblestones and readied glass bottles to be hurled at police.

The organizers called for a stop to the violence. "I am sad and I am appalled," said Ulrich Wilken, a spokesman for Blockupy. "This is not what the Blockupy groups had planned. … I understand the frustration and the anger and the desperation of the people though. … We have the ECB here which is responsible for the policy that brought misery over so many people. Their anger has now arrived in Frankfurt."