_ In San Francisco, about 200 people took over a vacant building owned by the local archdiocese and targeted in previous protests. Two men on adjacent rooftops lobbed pipes and bricks at officers.

Police said 26 protesters were arrested as officers in riot gear cleared the building early Wednesday.

Police Chief Greg Suhr told reporters he assumed some of the people inside the building were part of a group that vandalized shops, cars and a police station during a pre-May Day demonstration Monday night.

_ In Chicago, about 2,000 activists marched through the city to demand immigration reform and greater protections for workers. The crowd was much smaller compared to the half a million people who rallied in Chicago in 2006 to demand immigration reform.

_ In Los Angeles, a group that broke off from a downtown rally for immigration reform briefly skirmished with police and left an officer injured. Ten union demonstrators were arrested for blocking an intersection near Los Angeles International Airport.

Police Cmdr. Andrew Smith told KNBC-TV that an officer was hit in the helmet by a skateboard, but she was in good condition.

_ In Atlanta, about 100 people rallied outside the state Capitol, where a law targeting illegal immigration was passed last year. They called for equal rights for all workers and an end to local-federal partnerships to enforce immigration law.

The rally was significantly smaller than last year's, which drew about 1,000 people. Organizers said turnout last year was greater, in part, because the protest was on a Sunday, rather than during the workweek.

"I'm a bit disappointed, but I think this is something to be expected," said Adelina Nicholls, executive director of the Georgia Latino Alliance for Human Rights, one of the main organizers of the rally.

"It's very difficult to keep a high level of excitement going," Nicholls said. "But it's not only about mobilization. It's also about organization, and we have people working every day to promote immigrant rights."

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Contributing to this report were Associated Press photographer Eric Risberg in Oakland, and AP writers Samantha Gross, Colleen Long and Verena Dobnik in New York, Christina Hoag in Los Angeles, Peter Prengaman and Kate Brumback in Atlanta, Doug Glass in Minneapolis and Tammy Webber in Chicago.