PITTSBURGH - Protesters smashed shop windows and threw rocks at police on Thursday as police used pepper gas and batons to disperse marches against capitalism at the Group of 20 summit in Pittsburgh.
Protesters wore bandannas and goggles and held aloft a large black sign declaring "No hope in capitalism" and another saying "Kick Capitalism While It Is Down."
One sign simply said "I'm mad as hell."
Protests -- usually against some aspect of capitalism -- have often marked summits since trade talks in Seattle in 1999, when demonstrators ransacked the center of the city, targeting businesses seen as symbols of U.S. corporate power.
"We have seen police use rubber bullets, batons and gas," said Noah Williams, a spokesman for the anti-capitalist Pittsburgh G20 Resistance Project.
Officials said there were 15 arrests -- one for inciting a riot, four for aggravated assault and 10 others for failing to disperse.
Late on Thursday evening, several hundred protesters took to the streets near the Cathedral of Learning on the University of Pittsburgh campus. Police discharged gas and pellet-filled "beanbags" and protesters broke windows at a McDonald's, a Rite Aid pharmacy, a Subway sandwich shop and a FedEx store.
By midnight, hundreds of police in riot gear moved down Forbes Avenue. With no obvious protesters in sight, they sprayed pepper gas on passersby and even students looking down from the balconies of their residences above the avenue.
"We were just looking, then there were loud sirens and then it was hard to breath and I was coughing up a lung," said student Dustin DeMeglio, 19, who was watching as police moved by his apartment building.
Earlier, a crowd broke windows at Boston Market and KFC fast-food restaurants, a BMW dealership and a Fidelity Bank in the area, about a mile from the fenced-off convention center where the G20 talks were taking place.
Police in body armor with plastic shields threw pepper gas canisters and fired beanbags to disperse the protesters.
Leaders of 19 leading developed and developing economies and the European Union were meeting on Thursday and Friday to discuss how to avoid another global economic crisis.
Protesters planned a series of actions for Friday morning at locations including Starbucks, Gap, McDonald's and banks.
More than 12 hours of clashes on Thursday began when police dispersed some 2,000 people at a lunchtime march. With protesters sent down various streets by police, the two sides soon clashed in the Lawrenceville neighborhood.
Protesters threw bottles and rocks and police responded by sending five to 10 canisters into the crowd.
U.S. Secret Service spokesman Darrin Blackford said the gas used on Thursday was OC Vapor, which contains the active ingredient in pepper spray and causes the eyes to tear.
The marchers overturned dumpsters and hurled anything they could find at police, who gave chase and broke them into ever smaller groups.
"We're here to put pressure on the G20 to ultimately abolish global capitalism," said a 24-year-old man from Delaware, who declined to give his name.
Justin Hershkovitz, 26, a student from Michigan, complained about the police tactics as he ran from the officers.
"This kind of force has been used as an option of first resort by cops (at summits) in Italy, London and now Pittsburgh," he said. (Writing by Mark Egan; Editing by Frances Kerry)