Dozens of protesters were arrested early Thursday in the U.S. west coast city of Oakland after a largely peaceful strike called by the Occupy Oakland group on Wednesday went into chaos midnight. According to local TV reports, police dispersed crowds with tear gas and flash grenades after some people, mostly wearing black and covering their faces with bandannas, smashed windows, set fires and defaced downtown businesses with graffiti. Protesters clashed with police near their encampment site in a plaza outside the Oakland City Hall, leaving three protesters hospitalized and several police officers with minor injuries, said a report by the San Francisco Chronicle newspaper. Dozens of protesters temporarily took over a vacant two-story building near the encampment before midnight, hanging banners from the building\'s roof and defacing its exterior with spray-paint. Police had been keeping their distance from protesters most of the time Wednesday as they are under scrutiny for a clash last week leaving one protester with a serious head injury, which caught nationwide attention. But hundreds of police responded to the area late in the day after some protesters started a massive trash fire. Police said the flames, which reached some 4.6 meters high, may endanger residents in the area as well as some 500 people on the street. Early Thursday, some Occupy protesters helped clean up the mess in downtown Oakland. An organizer for Occupy Oakland told local TV that a small group of \"extremists\" and \"anarchists\" who don\'t represent the views of the movement, are the ones responsible for the destruction and clash with police. Thousands of protesters participated in the day-long general strike Wednesday in Oakland. Around 5,000 people marched to the Port of Oakland before sunset and clogged the main port entrance and seven other gates as the sun went down. Port officials said Wednesday night that maritime operations at the port, the fifth busiest container port in the U.S., were effectively shut down and dozens of trucks were unable to enter or leave. A small group of protesters still attempted to disrupt the operations of the port Thursday morning as they temporarily blocked an entrance to the port, but the fence they set up was later taken down. Oakland, located about 13 kilometers east of San Francisco, has a population of nearly 400,000 and ranks the eighth-largest city in the state of California.