About 400 anti-Wall Street protesters were arrested in New York when they blocked traffic on the Brooklyn Bridge, forcing authorities to shut it down for hours, police said. Anti-Wall Street activists first occupied a small park in lower Manhattan two weeks ago to protest corporate bailouts and corporate influence in politics, but took their demonstration to the bridge on Saturday. \"There were approximately 400 people arrested,\" a New York Police Department spokesman told AFP. \"The exact number is still being determined.\" Some were released after a few hours, while others would likely be held for a day, he said. Earlier, another NYPD spokesman said there were \"several hundred protesters who decided to walk on the roadway and who blocked traffic. Some heeded the warnings, some left, and arrests were made.\" The \"Occupy Wall Street\" group inspired by the pro-democracy Arab Spring movements had said on its website that \"at least 50\" protesters had been arrested. Police shut down the Brooklyn Bridge \"for a couple of hours\" in the late afternoon, the NYPD said, adding that many protesters had remained on the bridge\'s pedestrian walkway without incident. \"Occupy Wall Street\" said it had staked its ground in downtown Manhattan \"as a symbolic gesture of our discontent with the current economic and political climate.\" \"We are all races, sexes and creeds. We are the majority. We are the 99 percent. And we will no longer be silent,\" it added. Protesters have added police brutality to their lengthy and still vaguely defined list of grievances after a senior officer used pepper spray against four demonstrators who had already been shut inside a police pen a week ago. In Boston on Saturday, twenty-four protesters were arrested and charged with trespassing as a vast crowd marched outside Bank of America offices. Right to the City, the coalition of advocacy groups that organized the demonstration, said the event was held to protest corporate greed and to stop bank foreclosures. According to organizers, some 3,000 people marched outside the bank. Police did not provide a crowd estimate.